Mexican tycoon Carlos Slim has been ranked by Fortune magazine as the richest person in the world, beating Microsoft founder Bill Gates.Mr Slim, 67, is estimated to have $59bn (£29bn), while Mr Gates is said to have $58bn, the magazine reported.Mr Slim's wealth has grown by $12bn this year, based on the market value of the firms he owns.The ranking echoes an earlier rich-list by Mexican financial website Sentido Comun, which also put Mr Slim first. It's water off a duck's back to meCarlos SlimIn early July, the Mexican website said Mr Slim's fortunes had grown significantly after a 27% surge in the share price of his largest company, America Movil, in which he has a 33% share.