In an article from www.newsgeneration.com quoting Arbitron’s Radio Today, “the proportion of listeners with a college degree has risen at a rate of 26% the last decade, and the percentage of country listeners residing in households making $75,000 or more has risen more than 50 percent since 2002. That is one of the most significant shifts in all formats.”
http://www.newsgeneration.com/2013/01/09/country_radio_audience/