6,000 attended the 1973 New York convention .
15,000 attended in 1974 , much larger figures than at older events like the 4,500 at the 32nd Worldcon in 1974 .
6,000 attended the 1973 New York convention and 15,000 attended in 1974 , much larger figures than at older events like the 4,500 at the 32nd Worldcon in 1974 .