It is well-known that measuring the number of lines a programmer produces per year is a bad metric of his/her productivity.
For statistical purposes, I need a number of lines of lasting code a programmer touches annually. Here, a 'lasting' code line is a line that makes it into a released version, not just a beta version, and 'touching a line' means
(reading and (deleting or modifying or adding)) the line. Notice that 'touching a line' is equivalent to
((reading and deleting) or (reading and modifying) or (reading and adding)). The term
reading is difficult to count right, so I'm open to under- and overapproaximations of
reading and X which are better than the trivial
false ≤ (reading and X) ≤ X.
After getting the data, I would compute some average with error bars.
We are speaking about a programmer acting as a programmer, not as a reviewer who just reads someone else's code.
The used terms are, of course, imprecise. So please feel free to make them precise if you need that for your answer or to restrict them if your data is covering only a subindustry of software.