Year	Number of
1955	8674
1956	8698
1957	8728
1958	8750
1959	8855
1960	8990
1961	9141
1962	9371
1963	9626
1964	9881
1965	10110
1966	10300
1967	10470
1968	10640
1969	10860
1970	11150
1971	11360
1972	11620
1973	11840
1974	12010
1975	12150
1976	12210
1977	12210
1978	12230
1979	12240
1980	12270
1981	12270
1982	12260
1983	12270
1984	12310
1985	12390
1986	12400
1987	12420
1988	12510
1989	12660
1990	12830
1991	13020
1992	13230
1993	13490
1994	13740
1995	14030
1996	14300
1997	14500
1998	14670
1999	14770
2000	14830
2001	14790
2002	14700
2003	14580
2004	14390
2005	14110
2006	13730
2007	13360
2008	12940
2009	12640
2010	12400
2011	12270
2012	12210
2013	12180
2014	12190
2015	12060