In summary...

" ...in 2.4 we deleted 22,000 lines and added 600,000 lines. And in 2.6 we deleted 600,000 lines and added 900,000 lines. In the first six months. That's 1.5 million lines changed in a 6.2 million-line tree, a 64 MB diff in the first six months of the stable kernel. We changed a quarter of it!"

(Andrew Morton)