Year	Number of
1990	66.85
1991	68.88
1992	69.82
1993	70.95
1994	72.3
1995	73.89
1996	75.33
1997	76.9
1998	78.13
1999	79.15
2000	80.35
2001	82.11
2002	83.95
2003	86.87
2004	90.46
2005	92.89
2006	95.18
2007	96.67
2008	98.48
2009	100.36
2010	102.92
2011	106.26
2012	108.59
2013	111.31
2014	114.19
2015	117.24
2016	120.27