Year	Number of
1990	63.45
1991	64.5
1992	65.55
1993	66.41
1994	67.45
1995	68.64
1996	69.68
1997	70.85
1998	72.96
1999	74.92
2000	76.35
2001	76.49
2002	77.76
2003	79.75
2004	80.85
2005	81.3
2006	81.83
2007	81.86
2008	82.22
2009	82.9
2010	84.54
2011	85.59
2012	86.6
2013	87.29
2014	87.81
2015	88.19
2016	88.56