Year	Number of
1990	152.49
1991	173.64
1992	197.16
1993	225.29
1994	254.73
1995	284.76
1996	296.39
1997	307.72
1998	313.52
1999	317.39
2000	321.98
2001	328.14
2002	334.12
2003	341.42
2004	349.62
2005	358.46
2006	365.53
2007	373.41
2008	382.36
2009	392.39
2010	403.68
2011	414.81
2012	427.54
2013	440.52
2014	454.29
2015	468.65
2016	485.94