Year	Number of
1990	48.72
1991	51.21
1992	53.89
1993	56.79
1994	59.92
1995	63.31
1996	63.76
1997	64.29
1998	64.94
1999	65.58
2000	66.22
2001	67.03
2002	67.87
2003	68.96
2004	70.04
2005	71.15
2006	73.15
2007	75.15
2008	77.47
2009	79.9
2010	82.51
2011	86.61
2012	91.04
2013	95.91
2014	101.04
2015	106.42
2016	112.06