North American Soccer League (1968–84) - Attendance - Yearly average attendance stats

Reference 1: Lowest, Average, Highest and 2nd Highest.

Reference 2: 1968, 1969, 1970, 1971, 1972, 1973, 1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983 and 1984.

Source: http://en.wikipedia.org/wiki/North_American_Soccer_League_(1968%E2%80%9384)