In this letter from US ratings organisation the ERSB, president Patricia Vance shows that last year 94 percent of all rated games were pitched at the age of 13 or younger, with mature games accounted for only 6 percent of the market, down from 8 percent the previous year.
Ratings in general had risen by 22 percent year on year, she said.
"While a handful of M-rated titles tend to garner a majority of media attention, the E (Everyone 6+) rating category continues to dominate," she said. "The E category saw the largest increase over last year, accounting for nearly 60% of ratings assigned overall. The M (Mature 17+) category represented 6% of the overall ratings assigned, down from 8% in 2006 and 12% in 2005."
Full thing, including pretty charts, here.