Year	Number of
1990	57.03
1991	58.15
1992	59.39
1993	60.7
1994	62.02
1995	63.5
1996	64.58
1997	65.89
1998	67.46
1999	69.22
2000	71.14
2001	72.01
2002	73.15
2003	74.45
2004	75.95
2005	77.69
2006	79.93
2007	82.25
2008	84.89
2009	87.8
2010	91.08
2011	93.34
2012	96.13
2013	98.66
2014	101.43
2015	104.38
2016	107.67