http://en.wikipedia.org/wiki/Smartphone#Historical_sales_fig...
Microsoft sold 14 million smartphones (or rather, their device partners, probably mostly HTC back then) in 2007, but according to this article from 2007, RIM was running at about 9.6 million devices a year, which matches what wikipedia says:
http://www.computing.co.uk/ctg/news/1830466/blackberry-sales...
So at some point in 2007 Microsoft some crazy how had something like a third of the smartphone market.
I suspect fleet deployments were a big part of their sales.
I suppose that might be due to the market growing - in which case Apple looks like it's relatively flat starting around 2010 but in reality the number of users were increasing along with the market.