The outdoor pig industry has grown quickly over the last decade, a factor that has been hastened by the high capital costs of indoor pig housing as well as public demand for a less intensive industry. Planning regulations have also made it more difficult to develop indoor pig production. Pigs are farmed in many countries, though the main consuming countries are in Asia, meaning there is a significant international and even intercontinental trade in live and slaughtered pigs. Despite having the world's largest herd, China is a net importer of pigs, and has been increasing its imports during its economic development. The largest exporters of pigs are the United States, European Union, and Canada. As an example, more than half of Canadian production (22.8 million pigs) in 2008 was exported, going to 143 countries. Older pigs will consume eleven to nineteen litres (three to five gallons) of water per day.
