I don't know about the world, but in the U.S., Football (American Style) is number one by far. It is popular largely because it is played only once per week and is the most sought after sport for gambling.
Baseball is number two. Unlike football, there is little gambling involved.
Basketball is a strong Number three - gambling does play a prominent part in its popularity.
Hockey is Number four. I have never heard of gambling being involved with the sport.
There is no number five. Other sports are very minor compared to the big four. Other sports include golf, tennis, soccer, and bowling.