Linux
A 2001 study of Red Hat Linux 7.1 found this distribution had 30 million lines of code. The study showed that Red Hat 7.1 required about 8,000 years of time to develop. The study also said that if all this software had been made by proprietary means, it would have cost about $1.08 billion to make in the United States. As of March 7, 2011, Linux kernel would cost about $3 billion.