| Year | Underground/Surface work location | Number of employees | Employee hours | Full-time equivalent employees |
|---|---|---|---|---|
| 1983 | Underground | 105,518 | 183,510,810 | 91,755 |
| Surface | 268,396 | 475,065,991 | 237,533 | |
| Total | 373,914 | 658,576,801 | 329,288 | |
| 1984 | Underground | 109,402 | 196,849,735 | 98,425 |
| Surface | 278,935 | 508,276,231 | 254,138 | |
| Total | 388,337 | 705,125,966 | 352,563 | |
| 1985 | Underground | 103,297 | 188,118,683 | 94,059 |
| Surface | 273,013 | 493,085,151 | 246,543 | |
| Total | 376,310 | 681,203,834 | 340,602 | |
| 1986 | Underground | 95,497 | 174,827,405 | 87,414 |
| Surface | 262,263 | 477,647,125 | 238,824 | |
| Total | 357,760 | 652,474,530 | 326,237 | |
| 1987 | Underground | 87,678 | 163,081,304 | 81,541 |
| Surface | 261,299 | 480,851,605 | 240,426 | |
| Total | 348,977 | 643,932,909 | 321,966 | |
| 1988 | Underground | 85,109 | 159,803,188 | 79,902 |
| Surface | 268,730 | 496,104,970 | 248,052 | |
| Total | 353,839 | 655,908,158 | 327,954 | |
| 1989 | Underground | 83,494 | 157,042,823 | 78,521 |
| Surface | 276,135 | 506,122,818 | 253,061 | |
| Total | 359,629 | 663,165,641 | 331,583 | |
| 1990 | Underground | 84,720 | 162,603,128 | 81,302 |
| Surface | 280,062 | 509,778,293 | 254,889 | |
| Total | 364,782 | 672,381,421 | 336,191 | |
| 1991 | Underground | 77,175 | 148,993,479 | 74,497 |
| Surface | 272,207 | 485,548,664 | 242,774 | |
| Total | 349,382 | 634,542,143 | 317,271 | |
| 1992 | Underground | 72,323 | 138,544,192 | 69,272 |
| Surface | 265,264 | 474,546,699 | 237,273 | |
| Total | 337,587 | 613,090,891 | 306,545 | |
| 1993 | Underground | 63,663 | 118,617,630 | 59,309 |
| Surface | 258,291 | 463,486,612 | 231,743 | |
| Total | 321,954 | 582,104,242 | 291,052 | |
| 1994 | Underground | 65,473 | 124,458,125 | 62,229 |
| Surface | 266,133 | 477,311,335 | 238,656 | |
| Total | 331,606 | 601,769,460 | 300,885 | |
| 1995 | Underground | 61,534 | 119,471,864 | 59,736 |
| Surface | 263,061 | 477,489,493 | 238,745 | |
| Total | 324,595 | 596,961,357 | 298,481 | |
| 1996 | Underground | 58,898 | 117,557,570 | 58,779 |
| Surface | 260,643 | 479,517,532 | 239,759 | |
| Total | 319,541 | 597,075,102 | 298,538 | |
| 1997 | Underground | 58,123 | 116,164,608 | 58,082 |
| Surface | 267,413 | 483,296,428 | 241,648 | |
| Total | 325,536 | 599,461,036 | 299,731 | |
| 1998 | Underground | 56,262 | 111,751,258 | 55,876 |
| Surface | 264,912 | 480,110,133 | 240,055 | |
| Total | 321,174 | 591,861,391 | 295,931 | |
| 1999 | Underground | 51,564 | 102,383,418 | 51,192 |
| Surface | 265,770 | 474,307,797 | 237,154 | |
| Total | 317,334 | 576,691,215 | 288,346 | |
| 2000 | Underground | 48,444 | 95,128,274 | 47,564 |
| Surface | 264,279 | 468,654,511 | 234,327 | |
| Total | 312,723 | 563,782,785 | 281,891 | |
| 2001 | Underground | 50,467 | 100,299,668 | 50,150 |
| Surface | 262,089 | 461,368,170 | 230,684 | |
| Total | 312,556 | 561,667,838 | 280,834 | |
| 2002 | Underground | 47,485 | 92,050,735 | 46,025 |
| Surface | 248,541 | 433,975,618 | 216,988 | |
| Total | 296,026 | 526,026,353 | 263,013 | |
| 2003 | Underground | 44,125 | 89,556,629 | 44,778 |
| Surface | 243,392 | 424,226,502 | 212,113 | |
| Total | 287,517 | 513,783,131 | 256,892 | |
| 2004 | Underground | 46,360 | 96,365,895 | 48,183 |
| Surface | 249,457 | 445,677,193 | 222,839 | |
| Total | 295,817 | 542,043,088 | 271,022 | |
| 2005 | Underground | 50,732 | 106,081,050 | 53,041 |
| Surface | 260,395 | 471,128,545 | 235,564 | |
| Total | 311,127 | 577,209,595 | 288,605 | |
| 2006 | Underground | 53,620 | 112,092,026 | 56,046 |
| Surface | 275,162 | 491,669,814 | 245,835 | |
| Total | 328,782 | 603,761,840 | 301,881 | |
| 2007 | Underground | 55,617 | 114,443,292 | 57,222 |
| Surface | 286,491 | 497,389,379 | 248,695 | |
| Total | 342,108 | 611,832,671 | 305,916 | |
| Total | Underground | 1,716,580 | 3,289,796,789 | 1,644,898 |
| Surface | 6,642,333 | 11,936,636,609 | 5,968,318 | |
| Total | 8,358,913 | 15,226,433,398 | 7,613,217 |