Year	Number of
1990	35.42
1991	37.72
1992	39.82
1993	42
1994	44.45
1995	44.91
1996	45.08
1997	45.81
1998	46.45
1999	46.36
2000	48.17
2001	50.03
2002	51.6
2003	52.8
2004	53.59
2005	55.33
2006	57.19
2007	58.85
2008	60.89
2009	63.31
2010	64.71
2011	66.35
2012	68.18
2013	70.16
2014	72.62
2015	74.76
2016	77.12