Region
United States
1,172
California
763
Colorado
633
Pennsylvania
628
Wyoming
533
Utah
527
Nevada
493
Montana
454
Alaska
446
Arizona
337
New Mexico
321
Texas
321
Idaho
248
New York (State)
243
West Virginia
239
Michigan
222
North America
214
Virginia
205
Kentucky
201
Kansas
191
Illinois
182
New Jersey
177
Powder River Basin (Wyo. and Mont.)
170
Australia
158
Virginie-Occidentale
150
West (U.S.)
149
Ontario
144
Canada
142
Washington (State)
142
Ohio
135
États-Unis
132
South Africa
132
Missouri
125
Europe
124
Oklahoma
124
Indiana
117
Maryland
117
Middle West
115
Wisconsin
115
Great Britain
113
Appalachian Basin
110
China
110
Florida
108
Californie
103
France
103
Georgia
103
Mexico
100
Pennsylvanie
100
Oregon
95
Minnesota
94
more ...