I just took a look at a couple of sets of numbers I have available. The 2013 yearbook shows 269,777 baptized and 7,782,346 publishers, meaning baptisms equaled 3% of publishers.
The 1975 yearbook is one of the few publications I kept, which shows 2,021,432 publishers and 297,872 baptisms. Baptisms equaled 14% of publishers.
The really fun number is hours. In 1974 it took 1245 publisher hours to make a convert, last year it took 6506! So they are still sucking in a few people, although I think they are baptizing a lot more of their own kids at younger ages than they did back in the day. However, they are vastly less efficient at doing so.