Year	Number of
1990	55.94
1991	58.23
1992	60.41
1993	62.32
1994	64.2
1995	66.32
1996	68.8
1997	71.14
1998	72
1999	74.76
2000	75.13
2001	75.93
2002	77.32
2003	80.72
2004	83.75
2005	87.78
2006	89.94
2007	93.48
2008	96.76
2009	100.21
2010	103.63
2011	107.64
2012	112.25
2013	116.49
2014	120.99
2015	125.33
2016	129.35