Year	Number of
1990	68.84
1991	69.02
1992	69.23
1993	69.27
1994	69.38
1995	69.61
1996	69.42
1997	69.17
1998	69.06
1999	69.05
2000	69.18
2001	69.92
2002	70.83
2003	72.25
2004	73.78
2005	75.53
2006	77.1
2007	78.73
2008	80.44
2009	82.36
2010	84.57
2011	86.18
2012	88.2
2013	90.4
2014	93.05
2015	96.13
2016	99.97