It’s the result of a poll at the GDC (Game Development Conference), it shows the intent to develop for certain game platforms, they can vote as many platforms as they want. You see, PC and Smartphones get a 50%, PS4 a 20%… but the main reason it has become popular is the 4.4% of Wii U.
Well, the graphic makes a lot of sense with what we are seeing in the Wii U, not a lot of games! ^_^U… but, you have to put everything in perspective. All i have to say is, just look at the 3DS graph and make your own conclussions…