The recent Py2 vs Py3 survey over Christmas suggests that approx. 32% of respondents write in Python 3 (increasing on last year), 68% write in Python 2 (decreasing on last year). Py3 usage is up approx. 12% on last year's survey. For personal projects Py2 and Py3 have roughly equal popularity: http://www.randalolson.com/2015/01/30/python-usage-survey-20...

At monthly PyDataLondon meetings I remind the audience to switch to Py3 (a few do each month) as Py2's sunset date is less than 5 years away now.