Region
1955-
1
Africa --
2
Asia --
1
Asia, Southeastern --
2
China --
1
Developing countries
1
Developing countries --
3
Europe --
2
France
1
Germany (East) --
1
Germany (West) --
2
Great Britain
1
Great Britain --
2
Russia
2
Russia --
1
Soviet Union
1
Soviet Union --
4
Sweden
1
United State --
1
United States
4
United States --
14