Part 2 of this article focuses on each girl group individually, looking at their charting history on GAON's yearly digital chart.
Although Mr. Taxi's ranking was a steep drop, SNSD seems to have an up and down pattern with releases. Of course some of these were follow ups and released late in the year, but you can sort of see a pattern, which means I Got a Boy probably won't make it into the top 10 yearly but a follow up might do really well? Who knows, it could all be a coincidence and of course just the impact of how pubic friendly the songs are.
2NE1's slopes show that they tend to chart multiple songs but always at least one in the top 10, in fact had it not been for their #6 finish in 2012 with their only released song it would be a top 5 song every year. 2NE1 has had 12 songs charting, 11 in 2010 and 2011 alone. Like SNSD, 2NE1's most successful year 2009 is, unfortunately, not included to give better continuity since GAON started rankings in 2010.
How Dare You ranked #126 on the 2011 Chart so it likely would have ended up higher than Shady Girl had it not been released so late in the year. Taking that into consideration Sistar's trajectory is going up. With Sistar19 doing so well there is no reason to suggest Sistar won't continue to do well.
Kara has seen a fall but not as steep as AfterSchool despite an even heavier focus and greater success in Japan. Mister and Lupin were Kara's peak songs but again, GAON only started in 2010 so 2009's place in their trajectory is missing. A small drop in physical sales has also been observed so it may be that Kara's spot in this tier is in danger.
F(x) has remained stable after NUABO with their first two singles not ranking too well in 2009 but it seems their top 10 success with Pinocchio was an anomaly has all their other promoted title tracks have remained in the mid 20s.
Miss A had a huge debut which lead to a #1 ranking but have never been able to match the success although Baby Goodbye did manage a #11 ranking which is extremely good. Otherwise their title tracks Breathe, Touch and IDNAM performed poorly in comparison.
The Wonder Girls have been consistent, usually in top 10 or 20 and although Be My baby ranked lower it was released late in the year and it charted in 2012 as well at #197. Still they are not quite as high as they used to be and fallen a fair bit from their peak (Tell Me, Nobody). Also with the hiatus and focus on USA promotion, the fall makes sense.
The Brown Eyed Girls are a bit hard to place because of their non-idol status (to some) and their focus in recent years on solo projects which have been fairly successful (well, Ga-in and Narsha at least). Their last title track was not really promoted and their peak was in 2009 with Abracadabra. They really are a wild card.
T-ara has been all over the place but taking many things into consideration, such as that they often release songs at the end of the year, the graph may be slightly skewed. Their songs from 2009, Bo Peep Bo Peep and Like The First Time charted in 2010 but those rankings do not reflect their success. Their first huge hit may have been IGCBOY but their next promotions did poorly. Then of course they ranked #1 in 2011 with Roly Poly and all their songs have done extremely well since (including Cry Cry which ranked two years 167 in 2012 so its ranking in 2011 is a bit low because it did not have time to chart). However, since their scandal a downward trend can be seen, if that will continue or not will have to wait until their next set of promotions.
AfterSchool saw their peak with Because of You which was actually released late in 2009 but still managed to rank on 2010's yearly chart. That year they also managed their peak on GAON Yearly with Bang at #29. Since then it has been downhill with Flashback not even managing to break the Top 100, let's hope their next title track will do better and they focus more on Korea since some have said their Japanese activities are to blame for their poor showing. Others attribute it to the graduation system that now sees two new members who have not been able to make a name for themselves and the graduation of leader Kahi.
Orange Caramel generally kept just outside the 100s with their cute/aegyo style tracks, which includes Shanghai Romance which would have ranked slightly higher if it had more time to sell (released mid October). Their dance influenced tracks like Bangkok City and Lipstick seem to do much better. Overall they seem to grow or show stability while AfterSchool falls. This also shows that song/concept choice and promotions are likely to blame for AfterSchool's fall in rankings.
Secret had a whirlwind year in 2011 but none of their songs matched the rank of Startlight, Moonlight while Magic and Shy Boy saw similar rankings. Although Love is Move did not have much time to chart its unlikely it would have done much better than the 50s or 40s. Still this shows what a disappointing ranking Poison saw although its still within the top 100.
It is easy to see why 4Minute is seen as having fallen as they did not double promote songs last year and their one title track did about as well as their more poorly performing title track from 2011. It seems 4Minute really benefits from double track promotions but perhaps Hyuna's solo career is making that difficult although since 2YOON is doing decently maybe that won't matter for long.
Its seems like Girl's Day had one huge hit with Twinkle Twinkle and nothing that came close although Nothing Lasts Forever was the first song that got them attention after a terrible debut. I expect Expectation will lead the graph back in an upwards direction but how far up is the question?
Rainbow has seen a charting pattern of one song doing decently and then a follow up doing poor more poorly but managing to rank outside the top 100. Having been inactive as a whole in 2012 there is some concern that their popularity has dropped but Tell Me is doing decently. They have a good chance of moving up particularly if they have another set of promotions this year with similar success as they stand out in terms of ranking history compared to others in this tier.
Dal Shabet has also been stable with songs ranking in the mid to low 100s and as of yet unable to match the success of their debut song Supa Dupa Diva.
Out of this section Nine Muses has yet to rank on GAON's yearly top 200 but it is suspected they will this year. APink has ranked twice, first with I Don't Know in 2011 at #170 and with Hush in 2012 at #103 with My My being split between the two and not charting either year.
The groups with the most songs is 2NE1 from 2 albums + a digital single with 12 songs. Coming in second by only 1 song is T-ara with 11 songs from 5 albums or 9 if you include repackages. T-ara could be considered tied if one includes their duet with Davichi but since not all members participated, I decided that was in the realm of company collaborations such as CCM's Wonder Woman series. Still the two groups can be considered tied for the sake of not hearing about bias.
2NE1's digital success and stability on top of multiple rankings are the reason they are on the same tier with SNSD despite half the album sales in recent years. There is little doubt that SNSD's CFs and activities on variety shows and dramas have given them more public recognition and star power. That said 2NE1's international connections and popularity outside Asia along have also helped. At the end of the day it is because these two girl groups feature such radically different styles and seem to be almost the opposite of each other that they are a modern day SES and Baby VOX, rivals with each their own dedicated fanbase.
Hope you found the graphs and commentary useful!
(!) Sistar, SNSD and 2NE1's ranks come from overall but I switched to domestic only when I realized my mistake for all the others. Little would have been impacted, maybe those not ranking in top 100.