Region
Soviet Union --
Soviet Union
15
United States --
9
United States
6
Russia (Federation) --
5
Developing countries --
2
India
2
India --
2
Middle East
2
Middle East --
2
Singapore
2
Singapore --
2
Afghanistan --
1
China
1
China --
1
Developing countries
1
East Asia
1
East Asia --
1
Europe, Eastern
1
Europe, Eastern --
1
Japan
1
Japan --
1
Pakistan
1
Pakistan --
1
Russia
1
Russia (Federation)
1
South Asia
1
South Asia --
1
United states --
1