You are a browser extension developer but you don’t have idea of the progressing of downloads between browsers marketplace.
So with Mozilla is possible to have many other information like the review numbers, the average etc, so yes Mozilla win!
Except the flame I created a python script that scan both marketplace and generate a json for every extension with the downloads, in the config file, of the script. Next generate an html file with graphs for every extensions, with the total!
The repo is on: https://github.com/Mte90/ExtStoreStats
To see the results: https://mte90.github.io/ExtStoreStats/
So the next step on your install to have a cron that every day execute