Break Down is
Chrome 59.6%
FireFox 24.0%
Internet Explorer 9.9%
Safari 3.6%
Opera 1.6%
[1] http://www.w3schools.com/browsers/browsers_stats.aspSource, Chrome, Internet Explorer, Firefox, Safari, Opera, Other
StatCounter 48.7% 23.0% 19.6% 4.9% 1.4% 2.3%
W3Counter 38.0% 19.0% 16.8% 16.0% 3.2% 6.0%
Wikimedia 45.9% 11.7% 16.9% 7.1% 1.6% 16.8%
NetApplications 19.3% 58.3% 15.5% 5.2% 1.0% 0.4%
http://en.wikipedia.org/wiki/Usage_share_of_web_browsers
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Line charts over time of W3Counter data (although I am not sure if this excludes mobile or not): http://www.w3counter.com/trends
https://chrome.google.com/webstore/detail/tabs-outliner/eggk...
There's an add-on for simple vertical tabs, but I think this is even better.
BTW you can move the tab outliner itself to a tab and close the window.
If you haven't used it before, and if you're prone to having 10+ tabs open at a time, I highly recommend it. Although I warn you that you may never wish to use Safari or Chrome again...
Chrome used to have a similar feature built-in but they removed it ages ago.