Year	Number of
1990	145.8
1991	150.2
1992	155.86
1993	164.74
1994	173.21
1995	182.24
1996	194.65
1997	207.7
1998	218.88
1999	226.95
2000	236.7
2001	244.69
2002	249.51
2003	253.03
2004	256.94
2005	261.91
2006	266.98
2007	270.83
2008	273.94
2009	278.92
2010	284.16
2011	287.46
2012	295.88
2013	306.04
2014	319.13
2015	329.42
2016	340.9