Region
Canada
1
Canada --
2
Developing countries
1
Europe
8
Europe --
European Economic Community countries
2
European Economic Community countries --
2
Japan - --
1
Japan --
1
Russia (Federation)
1
Russia (Federation) --
1
Soviet Union
1
Soviet Union --
2
United States
10
United States - --
1
United States --
12
United states --
1