A couple of people have asked me to look up dramas currently airing and rank them by ratings. If people find this useful I can continue to do it, just so people have a place to easily see what dramas are popular.
Monday & Tuesday Dramas (10 pm):
#1 Horse Doctor: 20% - 22.9% (MBC) - started out with 8.7% - 10.7 % (ep. 33/50 rated)
#2 School 2013: 15.3% - 17.3% (KBS) - started out with 8% - 10% (ep. 15/16 rated)
#3 King of Ambition: 9.7% - 10.6% (SBS) - started out with 9.8% (ep. 4/24 rated) *runs at 9 pm
Currently Horse Doctor is 2nd or 3rd in its time slot, School 2013 is 4th and King of Ambition is 16th approximately.
Wednesday & Thursday Dramas (10pm):
#1 7th Grade Civil Servant: 14% - 15.9% (MBC) - started with 12.7% - 15.6% (2/20)
#2 Jeon Woo-Chi: 13% - 14.9% (KBS) - started with 14.1% - 15.1% (20/24)
#3 The Great Seer: 9% - 12.6% (SBS) - started with 7% - 8.1% (31/36)
Currently 7th Grade Civil Servant is 6th in its time slot, Jeon Woo-Chi is 7th and The great Seer is 16th.
Saturday & Sunday Dramas (8-8:40pm):
#1 My Daughter Seo-Young: 42.4% - 47.4% (KBS) - started with 19.3% - 23.3% (38/50) 1st
#2 My Love, Madame Butterfly: 11.1% - 14.2% (SBS) - stated with 9% - 10.6% (27/50) 11th
#3 Rascal Sons: 8.8% (MBC) - started with 7.7% - 9.4% (27/50) 19th
Saturday & Sunday Dramas (9:40-10pm):
#1 Cheongdamdong Alice: 14.8% - 18.6% (SBS) - started with 8.6% - 10% (16/16) 4th
#2 Hundred Year Inheritance: 13.9% - 17.6% (MBC) - started with 13.8% - 16.6% (6/50) 6th
#3 The King's Dream: 10.8% - 12.2% (KBS) - started with 12.2% - 12.9% (30/80) 12th
In terms of top dramas I would say My Daughter Seo-Young tops everything else by FAR, then its Horse Doctor then Cheongdamdong Alice and School 2013 are fairly tied. Certainly dramas that attract an older audience do much better than School 2013 which is geared mostly towards students/young people as a larger portion of the population are older than 30.
The worst performer, on this list of course, is The Great Seer. I did hear that it was supposed to be 50 episodes like many historical dramas but was shortened due to low ratings but I have no idea if that is true.
That 40%+ drama, My Daughter Seo-Young, is the one being followed up by the drama singer IU is said to be starring in, it has some mighty big shoes to fill. Cheongdamdong Alice replaced Five Fingers, which was supposed to star idol group T-ara's Eunjung, but it has now been rumoured that Eunjung is being considered for a role in the Incarnation of Money which is supposed to take over after Cheongdamdong Alice ends.
School 2013 is going to be followed up Ad Genius Lee Tae-Baekm, the name sort of reminds me of Baking King Kim Tak Gu which also ran on KBS. If the drama will be as successful is unsure but with Han Chae Young (Boys Over Flowers, A Man Called God, Changing Partners) on the cast, at least a few men will tune in for sure.
* There is a range in ratings as different rating services have different outcomes and there is a separation between Seoul and Nationwide and therefore ranks as well as rating vary somewhat. Ratings/rankings are for most recent episodes available.
** Most dramas air both days so Monday & Tuesday dramas run 2 episodes per week, one on Monday and one on Tuesday and so forth.
*** Time in brackets are start times of the dramas not airing time, so 8-8:40 pm means the dramas start at times between 8 and 8:40pm not that they run for 40 minutes.
**** no ratings available for Monday - Friday or cable dramas.