So, Shueisha just shared their media kit of this year. The company is a publisher of books, light novels, novels, magazines and many more products but they're more know for their manga magazines and the manga they publish. Here are some statistics for the demographics of their manga magazines. I can't just post all of it here since there's a huge amount of images so I'll link to this thread on twitter compiling all of them with a french translation.
The japanese link if there's interest:
http://adnavi.shueisha.co.jp/mediaguide/
The japanese link if there's interest:
http://adnavi.shueisha.co.jp/mediaguide/