Number of Workers
Year	No of Workers
1965	27,830
1966	29,020
1967	31,260
1968	31,480
1969	31,990
1970	33,060
1971	34,060
1972	34,520
1973	36,150
1974	36,370
1975	36,460
1976	37,120
1977	37,690
1978	37,990
1979	38,760
1980	39,710
1981	40,370
1982	40,980
1983	42,080
1984	42,650
1985	43,130
1986	43,790
1987	44,280
1988	45,380
1989	46,790
1990	48,350
1991	50,020
1992	51,190
1993	52,020
1994	52,360
1995	52,630
1996	53,220
1997	53,910
1998	53,680
1999	53,310
2000	53,560
2001	53,690
2002	53,310
2003	53,350
2004	53,550
2005	53,930
2006	54,720
2007	55,230