Attendance (from http://members.aol.com/bradleyrd/attendance.html) and winning percents (from Basketballreference.com), by team and by year. The files are all in MSExcel format. So, use your "Save Target As" command to save them to your hard disk.
American Basketball Association, 1967-68 to 1975-76 (Attendance, Winning Percents, Ticket Prices 1970-71, Team Prices)