Year	Number of
1990	49.12
1991	50.86
1992	52.15
1993	53.6
1994	55.55
1995	56.54
1996	57.85
1997	61.08
1998	62.9
1999	63.28
2000	65.12
2001	66.38
2002	68.3
2003	70.91
2004	70.92
2005	73.51
2006	74.7
2007	78.78
2008	81.35
2009	83.76
2010	86.88
2011	90.93
2012	94.96
2013	99.32
2014	103.79
2015	107.97
2016	113.26