Subject Region
United States
537
Great Britain
127
Europe
102
China
93
Developing countries
74
Latin America
57
India
47
France
41
Canada
37
Mexico
36
Asia
35
England
34
Japan
34
Soviet Union
31
Germany
30
America
26
Africa
24
Europe, Eastern
24
Pennsylvania
24
Peru
24
Ireland
23
Australia
20
Italy
20
Southern States
19
Africa, Sub-Saharan
18
California
16
North America
16
Pacific Area
16
Spain
16
Poland
15
Ecuador
14
London (England)
14
Russia
14
Colombia
13
Russia (Federation)
12
Caribbean Area
11
Israel
11
Brazil
10
Venezuela
10
Espana
9
Florida
9
Illinois
9
Netherlands
9
New York (State)
9
Wales
9
America Latina
8
Argentina
8
Chile
8
Georgia
8
Louisiana
8
more ...