Linux kernel: 13 million lines, over 5 patches per hour.
The latest version of the Linux kernel currently consists of approximately 13 million lines of code across over 33,000 files. The rate of development peaked with version 2.6.30 last year, which saw an average of 6.40 patches per hour. The rate declined to an average of 5.30 patches per hour in version 2.6.35.
Between version 2.6.30 and 2.6.35, approximately 19 percent of kernel development was done by independent contributors with no corporate affiliation.