The North-American Interfraternity Conference website is here:
http://www.nicindy.org/index.html
From their website:
Today, the NIC has 66 member organizations with 5500 chapters located on 800 campuses in the United States and Canada with approximately 350,000 undergraduate members
I couldn't find any information on the number of total men initiated into NIC fraternities though.
I hope this helped you!!!
L&L,
tx*princess