Year	Number of
1952	156300
1953	152600
1954	152300
1955	155100
1956	159000
1957	164000
1958	169000
1959	173100
1960	175900
1961	175300
1962	174200
1963	172200
1964	170300
1965	170100
1966	170500
1967	172000
1968	173400
1969	175600
1970	177500
1971	179000
1972	180800
1973	184300
1974	188300
1975	194300
1976	200400
1977	207000
1978	213700
1979	219800
1980	226000
1981	230400
1982	233300
1983	234700
1984	234500
1985	235700
1986	241300
1987	250600
1988	261900
1989	272400
1990	281000
1991	287200
1992	290100
1993	290100
1994	287000
1995	283500
1996	281300
1997	280500
1998	279000
1999	275800
2000	270400
2001	261900
2002	252700
2003	242200
2004	234200
2005	230500
2006	233700
2007	241000
2008	250000
2009	258000
2010	263200
2011	263300
2012	261000
2013	255800
2014	251100
2015	244700