You have a point, but I think in reality you can divide the figure by four or more; in many of the cases there is an instrumental, a backing/ band track (i.e. everything but the vocal), the vocal (acapella) and the final complete thing.
It possibly is true, when you consider a track like Suspicion, where there three known different versions and the intrumental too. If you take a song like the U/R Temptations 'Last one out is broken hearted', there are 4 diffent vocal takes; three by David Ruffin and one by Paul Williams all done in the same session.
60000 / 4 = 15000
15000 / 12 (1958 - 1970) = 1250
1250 / 52 weeks = 24
24 / 5 (not working at weekends) = 5 de novo songs a day
It would be interesting to know just how many Jobete songs there are registered @ BMI