Operating Operating Number of revenues income employees 1977 1,059 178 36,700 1978 1,437 238 39,000 1979 1,804 283 44,200 1980 2,368 383 55,500 1981 3,198 536 63,000 1982 3,881 585 67,100 1983 4,272 363 73,000 1984 5,584 395 85,600 1985 6,686 450 89,000 1986 7,590 829 94,700 1987 9,389 1,612 110,500 1988 11,475 1,635 113,900 1989 12,742 1,336 118,400 1990 12,943 13 116,900 1991 13,911 -588 115,100 1992 13,931 -2,136 107,900 1993 14,371 -237 89,900 1994 13,451 -1,996 77,800