Year	Number of
1980	35850
1981	36800
1982	37460
1983	37890
1984	38000
1985	37770
1986	37260
1987	36410
1988	35510
1989	35230
1990	35620
1991	35870
1992	36970
1993	38270
1994	39390
1995	39830
1996	39810
1997	39010
1998	37720
1999	36380
2000	35100
2001	34030
2002	33060
2003	32420
2004	31880
2005	31330
2006	30930
2007	30540
2008	30330
2009	29990
2010	29770
2011	29490
2012	29300
2013	29130
2014	29040
2015	28800