There's not a whole lot to cite, estimates are fairly rough since many analytics programs are javascript based. I can point you to the Firefox "Popular Extensions" section (https://addons.mozilla.org/en-US/firefox/browse/type:1/cat:a...) NoScript is #5 at 354,158 weekly downloads, and the NoScript page itself which claims 65,864,095 total downloads (https://addons.mozilla.org/en-US/firefox/addon/722). Then there are the corporate offices where javascript is disable by IT, or even worse, I've heard of cases where a business uses a proxy service that switches out .js files with empty files, which not only gets rid of the JS, but it also means that noscript tags aren't visible since JS is still enabled.

Whether that's significant or not is a matter of opinion. Most estimates I've seen are 3-6%, but should be taken with a big grain of salt. For sites I've worked on I tend to see about 2-4% of users using Google Chrome as their browser, for comparison.

I realize this doesn't help much.