Year	Number of
1990	60.1
1991	61.6
1992	63.74
1993	66.1
1994	68.63
1995	73.2
1996	75.31
1997	75.14
1998	75.14
1999	71.22
2000	67.64
2001	67.86
2002	67.25
2003	68.63
2004	68.97
2005	69.77
2006	71.19
2007	73.09
2008	74.33
2009	77.24
2010	79.87
2011	82.77
2012	86.38
2013	87.37
2014	88.05
2015	88.64
2016	89.66