Year	Number of
1990	67.6
1991	69.83
1992	71.25
1993	72.94
1994	74.95
1995	77.37
1996	79.81
1997	82.32
1998	83.9
1999	84.74
2000	86.45
2001	88.58
2002	90.36
2003	93.14
2004	96.78
2005	98.98
2006	101.31
2007	103.38
2008	105.8
2009	108.08
2010	110.86
2011	114.32
2012	116.75
2013	119.58
2014	122.53
2015	125.7
2016	128.83