Region
United States
16
United States --
11
Europe
4
Europe --
3
Former Soviet republics
3
Former Soviet republics --
3
Developing countries
2
Southeast Asia
2
Africa, Northeast
1
Asia
1
Asia --
1
Asia, Southeastern
1
Asia, Southeastern --
1
Canada
1
Caucasus, Northern
1
Central America
1
East Asia --
1
Europe, Central
1
Europe, Eastern
1
Germany
1
Germany --
1
Korea (North)
1
Korea (North) --
1
Korea (South)
1
Korea (South) --
1
Middle East --
1
Pacific Area
1
Pacific Area --
1
Russia
1
Russia (Federation)
1
Russia (Federation) --
1
Russia(Federation) --
1
Soviet Union --
1
Ukraine --
1
United Nations
1
United states --
1