Region
China
25
United States
23
Russia (Federation)
9
Soviet Union
7
Europe, Eastern
5
Japan
5
Europe
4
Developing countries
3
Former Soviet republics
3
Russia
3
Taiwan
3
Asia
2
European Economic Community countries
2
Latin America
2
America
1
Asia, Southeastern
1
Austria
1
Bosnia and Hercegovina
1
Communist countries
1
Czechoslovakia
1
East Asia
1
Eurasia
1
Europe, Central
1
Former Soviet Republics
1
Former communist countries
1
Germany (East)
1
Hungary
1
Korea
1
Korea (South)
1
Kwangsi Chuang Autonomous Region (China)
1
Lu-kang chen
1
Mexico
1
Moscow
1
Nanjing (Jiangsu Sheng, China)
1
Pacific Area
1
Poland
1
Shandong Sheng (China)
1
Sweden
1