Year	Number of
1963	167600
1964	170500
1965	171300
1966	169400
1967	165400
1968	160000
1969	154400
1970	150500
1971	148500
1972	147800
1973	148300
1974	148300
1975	147600
1976	146200
1977	144400
1978	142500
1979	140000
1980	137700
1981	134500
1982	131200
1983	126900
1984	122300
1985	116400
1986	110600
1987	103900
1988	97420
1989	90960
1990	85530
1991	80850
1992	77000
1993	73670
1994	71200
1995	69530
1996	68340
1997	67090
1998	66140
1999	64340
2000	61050
2001	56610
2002	52120
2003	47690
2004	43470
2005	39580
2006	35650
2007	32710
2008	30870
2009	30330
2010	30380
2011	30980
2012	31640
2013	31640
2014	30420
2015	28600