List of FIDE chess world number ones - Time at FIDE number one and youngest age at FIDE number one (through April 1, 2017)

Reference 1: Months at No. 1, Peak rating and Rating at first time No. 1.

Reference 2: Kasparov, GarryGarry Kasparov, Karpov, AnatolyAnatoly Karpov, Carlsen, MagnusMagnus Carlsen, Fischer, BobbyBobby Fischer, Topalov, VeselinVeselin Topalov, Anand, ViswanathanViswanathan Anand and Kramnik, VladimirVladimir Kramnik.

Source: http://en.wikipedia.org/wiki/List_of_FIDE_chess_world_number_ones