Seems like a really wide calling range, it's interesting to hear you end up with such a strong river range here, but I guess if you're flatting 3bet this much you're not 4b so much on the button? I also open 50%, I defend 21% of my button range (10% of total hands) by flatting, and 10.5% of my button range (5% of total hands) by 4betting, so my total defence range seems pretty similar - ie. about 15% of total hands, but I'm not flatting so wide.