Year	Number of
1990	425.96
1991	429.98
1992	435.72
1993	442.48
1994	450.32
1995	459.44
1996	467.54
1997	476.18
1998	483.93
1999	498.13
2000	507.92
2001	521.13
2002	522.01
2003	523.03
2004	525.52
2005	531.2
2006	531.86
2007	531.02
2008	536.8
2009	533.95
2010	535.19
2011	531.12
2012	534.31
2013	538.64
2014	543.25
2015	548.81
2016	555.96