| Year | Number of employees | Employee hours | Full-time equivalent employees |
|---|---|---|---|
| 1983 | 373,914 | 658,576,801 | 329,288 |
| 1984 | 388,337 | 705,125,966 | 352,563 |
| 1985 | 376,310 | 681,203,834 | 340,602 |
| 1986 | 357,760 | 652,474,530 | 326,237 |
| 1987 | 348,977 | 643,932,909 | 321,966 |
| 1988 | 353,839 | 655,908,158 | 327,954 |
| 1989 | 359,629 | 663,165,641 | 331,583 |
| 1990 | 364,782 | 672,381,421 | 336,191 |
| 1991 | 349,382 | 634,542,143 | 317,271 |
| 1992 | 337,587 | 613,090,891 | 306,545 |
| 1993 | 321,954 | 582,104,242 | 291,052 |
| 1994 | 331,606 | 601,769,460 | 300,885 |
| 1995 | 324,595 | 596,961,357 | 298,481 |
| 1996 | 319,541 | 597,075,102 | 298,538 |
| 1997 | 325,536 | 599,461,036 | 299,731 |
| 1998 | 321,174 | 591,861,391 | 295,931 |
| 1999 | 317,334 | 576,691,215 | 288,346 |
| 2000 | 312,723 | 563,782,785 | 281,891 |
| 2001 | 312,556 | 561,667,838 | 280,834 |
| 2002 | 296,026 | 526,026,353 | 263,013 |
| 2003 | 287,517 | 513,783,131 | 256,892 |
| 2004 | 295,817 | 542,043,088 | 271,022 |
| 2005 | 311,127 | 577,209,595 | 288,605 |
| 2006 | 328,782 | 603,761,840 | 301,881 |
| 2007 | 342,108 | 611,832,671 | 305,916 |
| Total | 8,358,913 | 15,226,433,398 | 7,613,217 |