The attendance figures and the enthusiasm of participants
shroud a worry that cuts across trade groups and business
associations: The number of pilots in the United States
has fallen 25 percent in the past 25 years. The number
of student pilots has plummeted 56 percent over the
same period -- from about 200,000 to 87,200 in 2005.
Only about 40 percent of today's student pilots will
get their licenses.

This clipped from an article that was also about Oshkosh...