Year	Number of
1990	42.84
1991	44.16
1992	45.66
1993	47.26
1994	48.99
1995	50.88
1996	52.01
1997	53.27
1998	54.62
1999	55.96
2000	57.25
2001	58.69
2002	59.94
2003	61.19
2004	62.57
2005	64.22
2006	65.44
2007	67.07
2008	69.07
2009	71.33
2010	73.8
2011	75.57
2012	77.47
2013	79.43
2014	81.58
2015	83.94
2016	86.32