Year	Number of
1990	29.49
1991	30.92
1992	32.39
1993	33.99
1994	35.66
1995	37.45
1996	39.81
1997	42.32
1998	44.98
1999	47.78
2000	50.72
2001	52.87
2002	54.82
2003	56.53
2004	58.22
2005	59.98
2006	61.89
2007	63.96
2008	66.24
2009	68.65
2010	71.18
2011	74.18
2012	77.33
2013	80.55
2014	83.8
2015	87.06
2016	91.12