Region
Great Britain
8
Tropics
8
United States
7
Australia
5
Developing countries
4
India
4
Asia
3
New Zealand
3
Africa
2
China
2
South Asia
2
Antarctica
1
Cold regions
1
Columbia River Watershed
1
Gangetic Plain (India and Bangladesh)
1
Guinea, Gulf of
1
Himalaya Mountains Region
1
Japan
1
Mediterranean Region
1
North America
1
Pakistan
1
Sierra Nevada (Calif. and Nev.)
1
South America
1
Soviet Union
1
Trinidad and Tobago
1
Western Australia
1
Zambia
1