How many lines of code does an average Linux kernel developer produce per year?

Based on estimates of the value of the Linux kernel (around 2200 Million Euros in 2011), the size of the kernel (in 2011, version 2.6 was current, with a bit less than 20 million lines of code), and average salary of kernel developers (for Germany, one could estimate 60,000 - 80,000 EUR/year for a mid to senior embedded developer, you can go to kununu.de and look for salary statistics for larger companies like Siemens as a reference), one can estimate the lines of new code that a full-time kernel developer produces - less than 1000 lines per year:

 value=2200000000
 cost_man_year = 60000
 lines_of_code= 20000000

 person_years = value / cost_man_year
lines_per_person_per_year = lines_of_code / person_years

I get to 545 lines per person-year that way.

The interesting question is: You can obviously type that in in half an hour. What do these software developers actually do all day? ;->