Year	Number of
1990	47.17
1991	48.19
1992	49
1993	49.74
1994	50.74
1995	51.54
1996	52.39
1997	53.98
1998	55.13
1999	56.19
2000	57.9
2001	58.6
2002	59.57
2003	60.95
2004	61.6
2005	63.12
2006	64.67
2007	67.08
2008	69.2
2009	71.6
2010	74.37
2011	77.79
2012	81.27
2013	84.93
2014	88.87
2015	92.97
2016	97.5