Ohloh
In a similar style to my Git vs. SVN answerGit vs. SVN answer, Ohloh has been crawled (only) three times by the Internet Archive's Wayback Machine, but July 2011 is unreadable:
August 2010
- Git: 26,485 repositories (11.3% of total)
- Mercurial: 2,548 repositories (1.1% of total)
- Ratio: 10.4:1.0
May 2011
- Git: 116,224 repositories (35.3% of total)
- Mercurial: 3,753 repositories (1.1% of total)
- Ratio: 31.0:1.0
February 2012
- Git: 124,000 repositories (26% of total)
- Mercurial: ?
June 2012
- Git: 134,459 repositories (27% of total)
- Mercurial: 11,238 repositories (2% of total)
- Ratio: 12.0:1.0
October 2013
- Git: 238,648 repositories (38% of total)
- Mercurial: 17,145 repositories (2% of total)
- Ratio: 13.9:1.0
April 2014
- Git: 238,648 repositories (38% of total)
- Mercurial: 17,628 repositories (2% of total)
- Ratio: 13.5:1.0
Eclipse Community Survey
Another source of data is the Eclipse Community Survey. Git values below are for Git/GitHub.
2009 (pdf)
- Git: 2.4%
- Mercurial: 1.1% (Note: Hg listed under "other" in 2009 report, but itemised in 2010 report)
- Ratio: 2.2:1.0
2010 (pdf)
- Git: 6.8%
- Mercurial: 3%
- Ratio: 2.3:1.0
2011 (pdf)
- Git: 12.8%
- Mercurial: 1.1%
- Ratio: 11.6:1.0
2012
- Git: 27.6%
- Mercurial: 2.6%
- Ratio: 10.6:1.0
2013
- Git: 30.3%
- Mercurial: 3.6%
- Ratio: = 8.4:1.0
2014
- Git: 33.3%
- Mercurial: 2.1%
- Ratio: = 15.9:1.0
Summary
These appear to show that, of the open source repositories registered on Ohloh, and of the developers using Eclipse, Git is a good order of magnitude more popular than Mercurial.
