> Mozilla publishes aggregated Firefox usage data in form of Active Daily Installs (ADIs) here (Update: looks like the site requires a login now. It used to be available publicly for years and was public until a few days ago). The site is a bit clumsy and you can look at individual days only so I wrote some code to fetch the data for the last 3 years so its easier to analyze (link).

These two things are probably related :)