Region
United States --
10
United States
7
Soviet Union
5
Soviet Union --
5
Great Britain
2
Great Britain --
2
China
1
China --
1
Developing countries
1
Developing countries --
1
Europe
1
Europe --
1
India --
1
Latin America --
1
Malaya --
1
Malaysia
1
Malaysia --
1
Middle East
1
Middle East --
1
Spain --
1
Turkey
1
Turkey --
1
United states --
1