Year	Number of
1990	69.35
1991	68.2
1992	63.43
1993	59.43
1994	57.88
1995	56.64
1996	56.29
1997	56.2
1998	56.44
1999	56.41
2000	56.91
2001	58.01
2002	59.64
2003	61.33
2004	63.15
2005	65
2006	66.69
2007	68.37
2008	70.16
2009	71.58
2010	73.33
2011	74.88
2012	76.63
2013	78.22
2014	79.92
2015	82.08
2016	84.62