English is a World standard official language and 100% english is a Most common.. Magento Modules | Magento Themes
#1 is English at 1.5 to 1.8 billion speakers while Mandarin is #2 at 1.2 billion speakers. From what I've heard the Chinese government is pushing their students to learn English,so in a few years it might reach 2 billion speakers.
I believe English is the most common. If not withing the next hundred years a great number of more people will be speaking English.