Hi,
I wrote a quick & dirty parser to compute statistics on *new* CPython core developer per year using the following page as data: https://devguide.python.org/developers/
2007: 15 2008: 19 2009: 11 2010: 20 2011: 12 2012: 9 2013: 4 2014: 10 2015: 2 2016: 5 2017: 2
Compare these numbers to Stéphane Wirtel's statistics on pull requests: https://speakerdeck.com/matrixise/cpython-loves-your-pull-requests
=> Number of active core developerson on GitHub pull requests: 27 (stats from February 2017 to October 2017) (I'm not sure of the meaning of this number, it's the number of core developer who authored pull requests, I don't think that it counts core developers who only made reviews.)
If you look at the size of the source code, it's still growing constanly since 1990: https://www.openhub.net/p/python/
2007: around 783k lines 2010: around 683k lines 2013: around 800k lines 2015: around 875k lines 2017: around 973k lines
The number of bugs is also constanly growing. Statistics on bugs since 2011: https://bugs.python.org/issue?@template=stats
2011: around 2500 open issues 2013: around 4000 open issues 2015: around 5000 open issues 2017: around 6200 open issues
The size of the CPython project is constantly growing as its complexity (technical debt? what is this? :-)), but the growth of core developers is slowing down.
I do consider that we need more people to handle the growing number of issues and pull requests, so the question is now how to find and "hire" (sorry, promote) them ;-)
Maybe we have a problem with mentoring. Maybe the CPython code base became too hard to train newcomers? Maybe we are too conservative? I don't know.
Victor