Year	Number of
1990	130.3
1991	139.53
1992	151.58
1993	167.79
1994	184.75
1995	200.99
1996	211.47
1997	219.74
1998	226.31
1999	234.01
2000	243.05
2001	253.19
2002	264.44
2003	277.08
2004	289.99
2005	302.56
2006	314.81
2007	325.65
2008	336.17
2009	346.98
2010	359.54
2011	371.94
2012	386.01
2013	400.46
2014	416.36
2015	432.39
2016	455.65