Subject Region
United States
238
Developing countries
26
Great Britain
25
India
24
California
19
Canada
18
Europe
18
Mexico
12
Brazil
11
China
11
Japan
11
Latin America
11
Québec (Province)
11
New York (State)
10
Pennsylvania
10
Australia
9
Ontario
9
England
8
Texas
8
Appalachian Region
7
Illinois
7
Louisiana
7
New York
7
Chicago
6
France
6
Africa
5
Alberta
5
British Columbia
5
Netherlands
5
Philadelphia
5
Soviet Union
5
Tropics
5
Argentina
4
Asia
4
Chesapeake Bay Region (Md. and Va.)
4
Chile
4
Ecuador
4
Indonesia
4
Massachusetts
4
New Orleans
4
North America
4
Russia (Federation)
4
Spain
4
Vancouver
4
Appalachian Region, Southern
3
Diablo Canyon
3
Europe, Western
3
Gujarat
3
Houston
3
Italy
3
more ...