Year	Total
1971	6651
1972	9348
1973	13160
1974	13600
1975	14270
1976	17660
1977	18880
1978	18920
1979	20330
1980	21140
1981	16720
1982	16980
1983	17210
1984	16410
1985	16060
1986	15640
1987	15530
1988	15150
1989	15280
1990	15640
1991	16360
1992	17520
1993	17170
1994	17620
1995	18240
1996	17670
1997	17550
1998	16960
1999	18580
2000	19680
2001	19850
2002	20270
2003	21200
2004	20750
2005	21060
2006	22320
2007	20750
2008	21130
2009	18940