30%, minimum. I was hired alongside a guy with a fantastic resume. He pushed zero lines of usable code in 4 months. When he left I purged about 20 files which were tests that were just completely commented out (but I guess those count for LOC according to github's crude measure). I would say that not only was he incompetent, he was worth negative (thankfully, nothing critical) - Maybe in order to cover his tracks? he had moved certain classes of tagged tests (e.g. skip, broken) to "ignore" status instead of 'yellow star'/red dot, I now, months after his departure, have a pr reverting those changes months after because I didn't notice he had done that. Thankfully it had not covered up any major defect in our codebase (someone could have left a corner case test as "broken" with the intent to fix it later and wound up forgetting to and sending it to prod).

But hey. Programming isn't that bad. In the physical sciences it was 60-70%.