Male artists tend to sell better physically than female artists and companies take advantage of this by releasing multiple physical albums per year. On the other hand very few female artists have released more than one physical album this year instead having more digital singles.
The high total of male groups physical sales are not only augmented by how much more they tend to sell but also by the fact that they release multiple physical albums. This is of course just sound marketing and the opposite trend will be seen with female artists and digital sales. However, it should be noted that with each new physical release comes a digital release and title track meaning that male artists are generally not promoting far fewer songs than female groups but that their sales tend to be lower, with some exceptions of course. Certainly this is the trend with idol male and female artists.
You will also notice that the female artists who have released multiple physical albums are rookies who are establishing themselves or artists that have seen a rise in their popularity this year such as Nine Muses and Crayon Pop. They are trying to bank on their new popularity, again smart marketing.
Total Male Artists with 2+ Physical Albums: 
Teen Top: 
Kim Jaejoong: 
Heo Young Saeng 
FT Island: 
So Ji Sub: 
Total Female Artists with 2+ Physical Albums: 
Nine Muses: 
Crayon Pop: 
Kim Yerim 
Girl's Day: 
Ladies' Code: