The TIOBE Programming Community mantains a programming language popularity index and its updated on a monthly basis. Its based on a combination of factor like availability of skilled engineers, courses and third party vendors. They have also make use of the search engines to calcuate the popularity. Here is the list taken from the TIOBE site :
- Visual basic
You can get the complete list of language populaity here. But remember that this list doesn't show the best language. Instead it shows what is popular. Many of my friends ask ask which language is study.. I would say, learn on core technology Java or .Net. But never stop there. You need know a combination to be known as the best!