Year	Number
1961	8000
1962	10000
1963	11000
1964	13000
1965	14500
1966	16000
1967	17500
1968	18000
1969	19000
1970	20000
1971	21500
1972	22940
1973	31673
1974	37800
1975	43900
1976	50000
1977	56062
1978	63500
1979	70942
1980	78000
1981	85000
1982	93051
1983	110000
1984	130000
1985	150000
1986	170000
1987	185000
1988	195981
1989	205000
1990	215000
1991	220000
1992	228005
1993	228200
1994	228400
1995	228600
1996	228800
1997	290000
1998	230000
1999	228000
2000	228000
2001	244448
2002	257008
2003	257098
2004	249637
2005	287365
2006	298000
2007	308422