28 visiting now: 12 USA 
4 China 
3 Argentina 
2 Russia 
2 Iraq 
1 Congo 
1 Ukraine 
1 Cote DIvoire 
1 Vietnam 
1 Pakistan 
1 Australia 
1 Peru 
4 China 3 Argentina 2 Russia 2 Iraq 1 Congo 1 Ukraine 1 Cote DIvoire 1 Vietnam 1 Pakistan 1 Australia 1 Peru