Kernel 3.3 reaches 15 million lines of code when 3.0 is promoted to long term kernel. This number includes the blank lines, comments, , documentation, scripts. The kernel hit 10 million line mark in October 2008.
The majority if the code is for the drivers over 50%, followed by arch, sound, network and library.
Linux 3.0, has been designated as a stable kernel, this will also be promoted to long-term kernel status.
I remember using 2.0.17 came with a Slackware distribution.