Region
20th century
1
Afghanistan
2
Africa
1
Africa, West
1
Akron
1
Akron (Ohio)
1
Alabama
3
Algeria
1
Alicante
1
Ann Arbor
1
Appalachian Region
1
Arab countries
9
Argentina
1
Arizona
1
Arkansas
2
Armenia
1
Asia
3
Asia, Central
1
Australia
10
Austria
1
Berlin
2
Berlin (Germany)
2
Birmingham
1
Bosnia and Hercegovina
1
Boston
4
Brazil
10
Burma
1
California
4
Cameroon
2
Canada
10
Cape Town (South Africa)
1
Caribbean Area
1
Cauca River Valley
2
Cauca River Valley (Colombia)
2
Chapel Hill
1
Chicago
7
Chicago (Ill.)
2
Chile
2
China
16
Colombia
17
Communist countries
1
Cuba
2
Czech Republic
1
Czechoslovakia
1
Dallas
2
Developed countries
1
Developing countries
5
East Asia
2
Egypt
1
England
21
more ...