Year	Number of
1990	68.02
1991	68.31
1992	68.74
1993	69.25
1994	69.87
1995	70.66
1996	70.68
1997	70.85
1998	71.12
1999	71.48
2000	72
2001	72.36
2002	72.85
2003	73.47
2004	74.18
2005	75.04
2006	76.1
2007	77.19
2008	78.5
2009	79.95
2010	81.61
2011	83.3
2012	85.21
2013	87.21
2014	89.41
2015	91.82
2016	94.35