Year	Number of
1990	30.01
1991	32.06
1992	34.16
1993	36.4
1994	38.73
1995	41.21
1996	43.14
1997	45.14
1998	47.13
1999	49.29
2000	51.73
2001	53.47
2002	55.22
2003	56.56
2004	58.08
2005	59.98
2006	62.82
2007	65.95
2008	69.29
2009	72.55
2010	75.86
2011	78.39
2012	81.2
2013	83.85
2014	86.65
2015	89.61
2016	93.15