Does anyone have good data about the mix of hiring in 2010 between full-time employees and contractors or contingent workers?

I've seen some articles claiming that the number of temps and contractors grew dramatically, and some predictions that within a few years the  workforce may be more than 25% contractors, but I can't seem to locate any credible sources with actual hiring/employment data.

I'd be very grateful to anyone that can either cite some valid statistics, or point me towards a source where I could dig it out myself.

Thanks!