Some interesting statistics on open source programming language based on TIOBE Programming Community Index.

Programming Language	First Released	Ratings Oct 2013
C	1972	17.25%
Java	1995	16.11%
C++	1980	8.66%
PHP	1995	6.09%
Python	1991	3.11%
JavaScript	1995	2.04%
Perl	1987	1.61%
Ruby	1993	1.25%
Groovy	2003	0.66%
Scala	2003	0.35%
Haskell	1990	0.25%

Source:

http://www.tiobe.com/tpci.htm

http://en.wikipedia.org/wiki/History_of_programming_languages