Year	Number of
1990	26.51
1991	27.64
1992	28.93
1993	30.41
1994	32.04
1995	33.86
1996	35.08
1997	36.48
1998	38.04
1999	39.55
2000	40.99
2001	41.79
2002	42.44
2003	43.03
2004	43.71
2005	44.58
2006	46.5
2007	48.58
2008	50.97
2009	53.56
2010	56.4
2011	58.96
2012	61.8
2013	64.92
2014	68.24
2015	71.73
2016	75.59