W3Schools is not a good source for actual usage statistics.

[zinthose]

This issue is more of a warning to those that would want to use this data to express browser usage percentages for reporting or coding standard initiatives as the data source only shows the data for clients that connect to the W3Schools website. People that connect to the website are usually developers as such are a bit more technically savvy than the average user, as such, this will skew any results derived.

Perhaps a a disclaimer should be added to the Readme.md to clarify this possible issue.

[zinthose]

Perhaps http://gs.statcounter.com/ would be a better source as they have a tracking agent on over 2 million sites global (per there faq) and they license their work under a Creative Commons Attribution-Share Alike 3.0 Unported License. This means that you are welcome to use any information provided by StatCounter Global Stats, but please ensure to credit them (with a link) anywhere you use the stats/data/graphs.

See more details involving statistical variance issues and further pertinent information at: https://en.wikipedia.org/wiki/Usage_share_of_web_browsers

[rufuspollock]

@zinthose thanks for the comment and that's a good suggestion to use that other data source.

Would you be interested to contribute the data or at least a correction to README re current data source?

/cc @Mikanebu so you can keep an eye on this.