Year	Number of
1990	60.76
1991	61.84
1992	63.15
1993	64.82
1994	66.37
1995	68.18
1996	69.18
1997	72.01
1998	74.33
1999	76.62
2000	78.84
2001	80.83
2002	82.81
2003	84.91
2004	86.9
2005	88.62
2006	90.68
2007	93.2
2008	95.06
2009	97.59
2010	100.12
2011	104.97
2012	108.74
2013	112.52
2014	117.13
2015	122.63
2016	128.21