According to IBM developerWorks, the top languages are the following.

• Java
• JavaScript
• Python
• C#/C++
• SQL
• Swift

Institute of Electrical and Electronics Engineers has its own list.

• Python
• C
• Java
• C++
• C#
• R
• JavaScript
• PHP
• Go
• Swift

Every site has different list, but IBM developerWorks and Institute of Electrical and Electronics Engineers are respectable sources.