I did a self-study on a project that lasted several months. I wrote down everything, including mis-typed characters, grammar errors, syntax errors, and semantic errors. I did a root cause analysis of the result. One general result is that I have a 3% error rate, regardless of activity. In fact I find that the delete key is by far the most important key on the keyboard, representing 3% of all of the characters I type.

One observation is the fully 1/2 of ALL the programming errors I made were due to copy/paste. Your mileage may vary but I doubt it.

Copy/paste is evil but it is so "low level", like the delete key, that you probably don't even think about it.

You may find it worthwhile to do a deep analysis of your personal error rate on some project. It is very enlightening. In fact, we ought to fund studies so we can get industry wide statistics.