From another site.

 

Pig farming in China is carried out in backyard, small, and

 

large commercial farms. The actual numbers of pigs raised

 

in China is not known exactly – local estimates and

 

estimates reported by the Food and Agriculture

 

Organization of the United Nations (FAO) for 2009–

 

2010 vary between 490 million and 618 million pigs. In

 

contrast, other Asian countries, such as Vietnam, the

 

Philippines and Thailand, which have similar overall pig

 

production characteristics, only produce 33 million,

 

13 million and 8 million pigs respectively.

I think the number one state in the USA is Iowa producing 33 million hogs.