Facebook’s 2017 stock surge has Mark Zuckerberg keeping some much-older company. With Facebook shares up nearly 50 percent this year, the company’s co-founder and CEO is now the world’s fifth-richest person, thanks to a fortune worth roughly $70 billion. That puts Zuckerberg, 33, between Mexican telecom mogul Carlos Slim Helu, 77, and billionaire U.S. investor