To put things in perspective, consider than from web browsers and languages, to their respective ill-fated mobile OS efforts, nothing Mozilla created has ever gotten more adoption than something MS created.
We're talking about Mozilla.
Netscape was a different company -- and besides we're discussing under the context of MS vs benevolent/FOSS entities.
https://www.w3counter.com/globalstats.php
Last month ff was ahead
Source: http://de.statista.com/statistik/daten/studie/13007/umfrage/... (German statistics office. Paywalled sadly, but you can see the first paragraph that describes Firefox market share at 52%.)