Year	Number of
1990	473.52
1991	478.47
1992	483.52
1993	487.98
1994	493.83
1995	501.2
1996	471.8
1997	443.97
1998	418.2
1999	394.05
2000	371.55
2001	380.34
2002	389.97
2003	402.11
2004	414.96
2005	428.38
2006	441.59
2007	454.52
2008	467.34
2009	481.47
2010	497.8
2011	498.94
2012	502.21
2013	505.87
2014	510.23
2015	515.05
2016	520.41