Year	Number
1970	25099850
1971	25443804
1972	25603858
1973	25359022
1974	25343436
1975	25098582
1976	24770556
1977	24314132
1978	23930970
1979	23487246
1980	23025590
1981	22558112
1982	22072812
1983	21574674
1984	21166264
1985	20873796
1986	20618528
1987	20462766
1988	20244352
1989	20015018
1990	19654152
1991	19339288
1992	19007966
1993	18901442
1994	18823548
1995	18707214
1996	19160660
1997	19020796
1998	19085522
1999	18913656
2000	18658912
2001	18364116
2002	18079102
2003	17927866
2004	17842328
2005	17985480
2006	18029304
2007	18187344
2008	18204824
2009	18153260
2010	18096532
2011	18062904
2012	18011430
2013	18134418
2014	18130622
2015	18272148
2016	18325406
2017	18533022
2018	18543732
2019	18509660
2020	18385786
2021	18153754
2022	18008638