Year	Number of
1990	403.54
1991	424.61
1992	439.28
1993	455.83
1994	465.81
1995	473.63
1996	478.85
1997	485.35
1998	483.61
1999	479.4
2000	481.98
2001	489.9
2002	498.16
2003	504.58
2004	510.49
2005	512.8
2006	515.71
2007	523.01
2008	534.42
2009	554.95
2010	571.17
2011	585.91
2012	600.6
2013	615.3
2014	631.5
2015	645.14
2016	656.56