Consider how Digia used to make money (taken from Qt's blog on this news item) *...

		eliben on March 7, 2011 \| parent \| context \| favorite \| on: Digia bought Qt licensing business from Nokia Consider how Digia used to make money (taken from Qt's blog on this news item) Employing hundreds of Qt experts, Digia has 7 years experience in providing top-class Qt competence, and is dedicated to continue and grow Qt Commercial relationships as well as to contribute innovation to the overall Qt LGPL and commercial community.

I'd take that "hundreds" and divide it by 4 to arrive at the upper bound of the number of actual Qt developers Digia have.