Year	Number of
1990	26.04
1991	27.41
1992	28.88
1993	30.44
1994	32.22
1995	33.93
1996	35.43
1997	36.87
1998	38.12
1999	38.72
2000	39.5
2001	40.24
2002	41.08
2003	41.56
2004	42.4
2005	43.26
2006	44.59
2007	46.09
2008	48.2
2009	50.02
2010	51.93
2011	53.85
2012	56.05
2013	58.38
2014	60.5
2015	62.77
2016	64.77