I last looked at the BBM archives at Ryerson in 2006. At that time they had all the radio and television books dating back to 1995 available for public viewing, with older books being located in closed stacks accessible only to Ryerson students and staff. The Ryerson Library website now implies that all BBM books are located in the closed stacks.
I'm in Toronto right now so if I have time this week I'll make a visit to that library and see if that is actually the case.
I personally find it bizarre how BBM, over time, has become more and more secretive with its ratings data. They used to list a lot more TV ratings data back in 2004 and 2005 than they do now. First they got rid of the Top 10 programs by market for each ratings period (which revealed how highly rated local news was compared with network programming), then they got rid of the weekly Top 10 programs for Toronto and other large markets, leaving only the national weekly Top 10. Even Arbitron is more secretive than it used to be with its data; used to be anyone could access their ratings data by market, but now you have to register and be approved. I think that while detailed data should not be necessarily available to the public, some top-line data should be available to the public, other than just the bare minimum top-line data for medium and large markets for radio, and nationally for television.