Year	Number of
1990	263.02
1991	293.03
1992	325.11
1993	362.85
1994	400.09
1995	436.51
1996	443.29
1997	449.63
1998	448.17
1999	449.16
2000	450.28
2001	451.98
2002	452.4
2003	452.95
2004	452.13
2005	450.53
2006	448.55
2007	448.32
2008	449.82
2009	452.7
2010	455.87
2011	462.49
2012	471.02
2013	477.89
2014	487.51
2015	505.8
2016	530