| Year | Number of employees | Employee hours | Full-time equivalent employees |
|---|---|---|---|
| 1983 | 414,860 | 730,398,053 | 365,199 |
| 1984 | 427,887 | 775,212,899 | 387,606 |
| 1985 | 415,161 | 748,692,857 | 374,346 |
| 1986 | 394,805 | 717,707,252 | 358,854 |
| 1987 | 386,312 | 708,929,792 | 354,465 |
| 1988 | 391,700 | 722,562,534 | 361,281 |
| 1989 | 399,478 | 732,331,996 | 366,166 |
| 1990 | 404,315 | 740,784,377 | 370,392 |
| 1991 | 388,784 | 701,608,246 | 350,804 |
| 1992 | 377,695 | 679,979,765 | 339,990 |
| 1993 | 360,503 | 645,833,063 | 322,917 |
| 1994 | 369,143 | 665,859,155 | 332,930 |
| 1995 | 361,647 | 660,553,197 | 330,277 |
| 1996 | 355,496 | 659,969,250 | 329,985 |
| 1997 | 362,344 | 663,248,294 | 331,624 |
| 1998 | 357,315 | 655,039,983 | 327,520 |
| 1999 | 353,341 | 638,149,185 | 319,075 |
| 2000 | 348,548 | 624,888,489 | 312,444 |
| 2001 | 347,228 | 620,978,232 | 310,489 |
| 2002 | 329,114 | 582,678,793 | 291,339 |
| 2003 | 320,149 | 569,218,542 | 284,609 |
| 2004 | 329,008 | 598,165,329 | 299,083 |
| 2005 | 344,837 | 635,057,906 | 317,529 |
| 2006 | 363,497 | 662,515,881 | 331,258 |
| 2007 | 378,123 | 673,525,094 | 336,763 |
| Total | 9,281,290 | 16,813,888,164 | 8,406,944 |