Year	Number of
1990	66.57
1991	68.59
1992	70.31
1993	73.25
1994	76.6
1995	80
1996	81.95
1997	78.89
1998	77.91
1999	77.75
2000	76.99
2001	75.8
2002	74.31
2003	74.77
2004	75.21
2005	76.19
2006	77.32
2007	78.31
2008	79.01
2009	78.86
2010	79.71
2011	80.34
2012	80.23
2013	80.22
2014	80.25
2015	81.58
2016	82.71