Year	Number of
1990	41.49
1991	42.64
1992	44.18
1993	45.24
1994	46.55
1995	48.08
1996	49.31
1997	50.74
1998	52.66
1999	54.57
2000	56.31
2001	56.58
2002	56.98
2003	59.07
2004	61.4
2005	63.12
2006	64.22
2007	65.29
2008	66.18
2009	67.32
2010	68.8
2011	70.48
2012	72.11
2013	73.7
2014	75.2
2015	76.48
2016	78.5