Here's a good page about 2013's radio trends:
http://www.arbitron.com/downloads/Ra...13_execsum.pdf
Pop radio does very well with females in the 25-34 year-old range. This is also the demographic to target in terms of advertising, which is probably why pop stations are the most numerous and the most successful.
Rhythmic radio has the youngest audience of all radio formats, but in 2013 it increased with 25-34 year-old too. It also most diversity in its listeners in terms of race. It has the most equal distribution of black, hispanic and white listeners of any format.
Urban AC had its highest audience figures ever in 2013. It's also the format with the highest percentage of black listeners.
HAC also got its highest audience figures ever in 2013 (and apparently is getting more popular with teenagers).
Triple A and the rock formats do best with older males (25-54 years old), as expected.