15 mega-billionaires who made a fortune last year

Bill Gates is once again the richest man in the world, adding another $10.6 billion to his net worth in the past year. Not a bad haul, but four other billionaires actually outearned Gates in the past year. 
Using data from the Bloomberg Billionaires Index, which recently relaunched and expanded online to include 500 billionaires across the globe, Business Insider ranked which of the 30 richest billionaires in the world gained the most wealth in the past year.
Bloomberg's rank