Year	Number of
1990	59.64
1991	60.68
1992	61.24
1993	62.1
1994	63.33
1995	64.07
1996	65.37
1997	66.35
1998	66.97
1999	69.2
2000	69.81
2001	69.65
2002	68.95
2003	69.52
2004	68.1
2005	70.33
2006	74.82
2007	77.67
2008	80.29
2009	82.4
2010	84.19
2011	85.47
2012	86.74
2013	87.39
2014	88.37
2015	89.25
2016	90.02