Is that salary estimate also from 2011?
There’s a more robust methodology here, which is to look at commit history, but that will only tell you how many lines were pushed and merged. That will be a greater number, by the way: say the kernel is 100 lines, somebody may have written 50, but they may have all been replaced by future patches, so The number of lines written is greater than the number of existing lines.
Regardless, I’m sure you already know lines of code is a bad metric of output, let alone effort and work.
Ah, OK. What’s the expectation these days, if you don’t mind me asking?