I think America is too culturally diverse to make any kind of valid generalization(s). Probably the best way to gauge that would be to look at the average age of large country concert goers or who tunes in to say, the Country Music Awards. We know that Hip Hop or Rock concerts are going to be populated almost 100% by young people (along with a few nostalgia-heads) and 'traditional' artists ie. Celine Dion or Tony Bennett (unless GaGa is with him ) will draw an older crowd. Obviously, there are many other factors as well, such as geography. JMO.

chas