Year	Number
1972	12684187
1973	12825158
1974	13025471
1975	12891154
1976	12773726
1977	12676531
1978	12688969
1979	12740396
1980	12642303
1981	12633098
1982	13146766
1983	13298869
1984	13694787
1985	14107062
1986	14401082
1987	15104314
1988	15507346
1989	16327797
1990	17170776
1991	17188958
1992	18037844
1993	18651600
1994	18883802
1995	19027368
1996	19561568
1997	19018952
1998	19385276
1999	19682808
2000	19397060
2001	18834228
2002	17830796
2003	17020840
2004	16225544
2005	15522169
2006	14644206
2007	14054007
2008	12738581
2009	12803474
2010	13200000
2011	12800000
2012	12300000
2013	12100000
2014	11700000
2015	12100000
2016	12200000
2017	12500000
2018	13100000