Bloomberg tracks the fortunes of some 2,800 billionaires. Of those, 145 are worth at least $10 billion, making them decabillionaires. Now, the world contains two centibillionaires simultaneously. Microsoft Corp. co-founder Bill Gates, once the world\u2019s richest person, has again eclipsed the $100 billion threshold, joining Amazon.com Inc.\u2019s Jeff Bezos in the exclusive club, according to the Bloomberg Billionaires Index. Gates\u2019s fortune, now $100 billion on the nose, hasn\u2019t reached such heights since the dot-com boom, when 55-year-old Bezos was only beginning his march up the world\u2019s wealth rankings. The Amazon founder is now worth $145.6 billion, having added $20.7 billion this year alone, while 63-year-old Gates has gained $9.5 billion. These two fortunes underscore a widening wealth gap in the U.S., where those with the most capital are accumulating riches the fastest. It\u2019s also a worldwide trend. France\u2019s Bernard Arnault has an $86.2 billion fortune, equal to about 3 percent of his country\u2019s economy. The net worth of Spain\u2019s Amancio Ortega represents 5 percent of that nation\u2019s gross domestic product. And then there\u2019s Bidzina Ivanishvili, whose worth about a third of Georgia\u2019s GDP. The Gates and Bezos mega-fortunes may not last long. Gates has donated more than $35 billion to the Bill & Melinda Gates Foundation and said he intends to give away at least half of his wealth. Bezos, meanwhile, may be about to cede some of his fortune for a different reason: he and his wife Mackenzie are divorcing.