I think a much more relevant (but ultimately completely unmeasurable) metric is the number of websites currently rolling out (i.e. "upgrading to" or building af

I think a much more relevant (but ultimately completely unmeasurable) metric is the number of websites currently rolling out (i.e. "upgrading to" or building afresh on) jQuery. The vast majority of sites in any statistic like the above are always going to be older no-longer-very-actively-being-updated-beyond-maybe-some-security-patches frontends. An interesting indicative stat would be number of installs of the very latest jQuery versions.