What is the Marketshare of the big three video editing (NLE) software packages?
This kind of data is actually remarkably hard to come by.  There are a few industry reports available for thousands of dollars, but the best free resource I could find when I was searching was an informal poll that Dave Dugdale did.  It was an imperfect test by his own admission because it allowed both voting up and voting down, but it gives at least some kind of an idea of the rough market share.