Year	Number of
1990	57.51
1991	58.17
1992	58.8
1993	59.28
1994	60.13
1995	61.49
1996	61.9
1997	62.74
1998	63.98
1999	65.15
2000	66.14
2001	66.07
2002	65.89
2003	66.04
2004	66.2
2005	66.47
2006	68.73
2007	71.08
2008	73.61
2009	76.31
2010	79.21
2011	80
2012	80.89
2013	81.72
2014	82.66
2015	83.71
2016	84.67