I'll bite.
From the bottom of the summary here: http://en.wikipedia.org/wiki/Symbian#integrated_Symbian_plat...
We get: http://www.appleinsider.com/articles/09/08/21/canalys_iphone...
Symbian OS had 50% of the smartphone market as of August 2009. And 50% of the market in that dataset is a majority - probably a good enough a citation for "C++ was the mobile world" when you consider what that would have looked like before the iPhone.