There are many sixth grades that play football, but cannot be exactly counted due to the amount fo recreational, travel and school teams worldwide.
FOOTBALL (The one they actually play with feet ;)
120 million amateur players worldwide
1
100000000
200
Not me, sooo...
2
200000
Football (Soccer) is the most popular and widely played sport worldwide. It is also the most commercialised giving it a multi-billion dollar lead over any other sport in the world.
Worldwide, there are literally billions more people who play and watch football than those who watch American football. The US is the only country where American football is more popular than football.
Worldwide information is not readily available.