Table 04. Number of HOURS WORKED
at Coal Mines in the United
States, by Primary Activity, 1978-2006
|
|
Underground
Mines
|
Surface
Mines
|
|
Year
|
Underground
|
Surf
at UG
|
Total
|
Strip
|
Auger
|
Culm
Bank
|
Dredge
|
Total
|
|
1978
|
193,794,718
|
23,569,960
|
217,364,678
|
128,683,555
|
731,435
|
378,060
|
23,922
|
129,816,972
|
|
1979
|
230,304,102
|
26,522,638
|
256,826,740
|
135,510,409
|
598,590
|
438,467
|
57,738
|
136,605,504
|
|
1980
|
222,870,843
|
25,675,431
|
248,546,274
|
135,138,201
|
435,796
|
444,437
|
93,698
|
136,112,132
|
|
1981
|
200,772,943
|
23,277,349
|
224,050,292
|
130,576,920
|
397,004
|
415,581
|
139,598
|
131,529,103
|
|
1982
|
202,557,495
|
22,954,235
|
225,511,730
|
126,125,400
|
467,057
|
541,853
|
138,659
|
127,272,969
|
|
1983
|
155,494,125
|
18,744,636
|
174,238,761
|
115,456,732
|
570,423
|
442,954
|
156,531
|
116,626,640
|
|
1984
|
168,158,329
|
19,445,063
|
187,603,392
|
126,303,153
|
549,037
|
488,186
|
158,823
|
127,499,199
|
|
1985
|
162,461,265
|
19,576,115
|
182,036,880
|
116,870,526
|
648,976
|
469,398
|
126,150
|
118,115,050
|
|
1986
|
151,166,953
|
19,034,396
|
170,201,349
|
109,267,927
|
608,980
|
589,878
|
112,868
|
110,579,653
|
|
1987
|
139,667,922
|
16,649,387
|
156,317,309
|
105,119,295
|
878,387
|
654,963
|
150,384
|
106,803,029
|
|
1988
|
133,721,086
|
16,060,832
|
149,781,918
|
100,834,103
|
969,369
|
588,348
|
170,408
|
102,562,228
|
|
1989
|
130,635,823
|
16,473,421
|
147,109,244
|
100,595,934
|
875,864
|
675,184
|
199,502
|
102,346,484
|
|
1990
|
136,021,939
|
17,325,525
|
153,347,464
|
102,862,419
|
836,174
|
791,649
|
192,039
|
104,682,281
|
|
1991
|
124,435,749
|
16,546,316
|
140,982,065
|
94,544,458
|
882,922
|
755,464
|
141,238
|
96,324,082
|
|
1992
|
116,013,668
|
16,251,448
|
132,265,116
|
92,377,668
|
799,054
|
857,272
|
114,879
|
94,148,873
|
|
1993
|
97,713,848
|
15,473,757
|
113,187,605
|
86,027,291
|
862,951
|
1,064,394
|
72,118
|
88,026,754
|
|
1994
|
102,556,106
|
15,206,980
|
117,763,086
|
87,518,041
|
936,203
|
929,062
|
97,912
|
89,481,218
|
|
1995
|
96,348,584
|
14,004,507
|
110,353,091
|
80,293,088
|
922,842
|
924,278
|
110,028
|
82,250,236
|
|
1996
|
93,530,286
|
13,833,572
|
107,363,858
|
78,168,209
|
1,162,645
|
891,821
|
174,130
|
80,396,805
|
|
1997
|
91,949,818
|
13,802,276
|
105,752,094
|
79,634,049
|
1,253,071
|
925,869
|
145,678
|
81,958,667
|
|
1998
|
88,231,397
|
12,925,813
|
101,157,210
|
78,434,109
|
1,175,045
|
862,405
|
384,511
|
80,856,070
|
|
1999
|
|
