Year	Number of
1990	57.28
1991	58.34
1992	59.47
1993	60.7
1994	62.05
1995	63.58
1996	65.42
1997	67.46
1998	69.78
1999	72.3
2000	75.05
2001	77
2002	79.16
2003	81.51
2004	84
2005	86.65
2006	89.31
2007	92.05
2008	94.99
2009	98.14
2010	101.58
2011	104.07
2012	106.81
2013	109.69
2014	112.8
2015	116.15
2016	119.83