Year	Number of
1990	43.16
1991	43.37
1992	43.62
1993	43.83
1994	43.96
1995	44.21
1996	45.59
1997	47.01
1998	48.44
1999	49.88
2000	51.35
2001	53.52
2002	55.8
2003	58.23
2004	60.86
2005	63.81
2006	66.9
2007	70.03
2008	73.47
2009	77.1
2010	81.09
2011	82.77
2012	84.54
2013	86.39
2014	88.47
2015	90.64
2016	92.96