I agree, I also wish he would give actual numbers, rather than points on log chart, which are very hard to estimate by eye.
But to be fair, even with that, I doubt you would get more than 30% of Python 3 users. Which is kinda in line with other surveys, such as the one from JetBrains. (It's probably a good guess that users of Python applications are even more conservative in upgrading than developers of Python applications.)
Here is one recent one: http://www.randalolson.com/2016/09/03/python-2-7-still-reign...
If you have counter statistics showing that Python 3.x is more popular than 2.7 I would very much like to see them.