The other relevant metric is the distribution of speakers. Most of the speakers of Chinese live in China, but English is a significantly common language in 67 c

The other relevant metric is the distribution of speakers. Most of the speakers of Chinese live in China, but English is a significantly common language in 67 countries by Wikipedia's admittedly questionable estimation: http://en.wikipedia.org/wiki/List_of_most_widely_spoken_languages_(by_number_of_countries%29 http://en.wikipedia.org/wiki/List_of_most_widely_spoken_lang... I don't think the data is entirely trustworthy -- it seems unlikely that "Turkic" is spoken substantially in Lithuania -- but I did some analysis based on this data anyhow: http://adambard.com/blog/what-language-should-you-learn/ http://adambard.com/blog/what-language-should-you-learn/