Several students have come to the reference desk seeking demographics of those who attend NY Yankees baseball games. This is rather difficult information to find since the Yankees are privately held. (Perhaps students could try calling the Yankees' information office to see if this information is available. Asking people who attend the last games this weekend at the stadium may not be typical as it is the final series in the stadium.) I could not locate any statistical information about attendees on the Major League baseball website but once again, perhaps a phone call might be helpful.
Although the statistics are from 1998, the NYC Independent Budget Office produced some reports about attendees of games when NYC aid for construction of the new stadium was being considered. This report and others about the Yankees can be found at the IBO's web site and then search "Yankees."
HispanicBusiness had an article in July 2008 regarding the importance of Hispanic fans to baseball, which includes some information about the NY Yankees.
Hearing from Yankees fans, might also be possible through blogs. The economics of Yankees tickets, has some interesting comments, including that regular Joes have been priced out of the stadium, including many residents of the Bronx. Other comments include that regular families can only afford to attend one game a year.
I found some articles searching Factiva about how the Yankees led in attendance.
If anyone has any other ideas, please contribute.