A study by a leading MIT economist finds that learning a foreign language will increase your earnings by 2% on average. Learning German brings the greatest financial reward at 3.8%.
"Albert Saiz, the MIT economist who calculated the 2% premium, found quite different premiums for different languages: just 1.5% for Spanish, 2.3% for French and 3.8% for German. This translates into big differences in the language account: your Spanish is worth $51,000, but French, $77,000, and German, $128,000. Humans are famously bad at weighting the future against the present, but if you dangled even a post-dated $128,000 cheque in front of the average 14-year-old, Goethe and Schiller would be hotter than Facebook." (From Prospero column, "Johnson: What is a Foreign Language Worth," The Economist, March 11, 2014)
Read the entire Economist article on this study here.