Region
20th Century
1
Afghanistan --
1
Africa --
1
Africa, Northeast
1
Asia, Southeastern
1
Asia, Southeastern --
1
Australia
1
Australia --
1
Caucasus, Northern
1
Central America
1
Developing countries
1
Developing countries --
1
East Asia
1
East Asia --
1
Europe --
1
Great Britain
1
Great Britain --
1
Russia(Federation) --
1
Soviet Union
1
Soviet Union --
1
United States
4
United States --
6
United states --
1