Year	Number of
1990	42.33
1991	43.07
1992	43.92
1993	45.1
1994	46.3
1995	47.64
1996	48.52
1997	49.52
1998	50.56
1999	51.92
2000	53.3
2001	54.34
2002	55.45
2003	56.55
2004	57.69
2005	59.01
2006	60.24
2007	61.55
2008	63.05
2009	64.69
2010	66.49
2011	68.06
2012	69.78
2013	71.06
2014	72.45
2015	74.04
2016	75.67