Year	Number of
1990	35.61
1991	37.09
1992	38.66
1993	40.38
1994	42.2
1995	44.15
1996	44.58
1997	45.05
1998	45.63
1999	46.25
2000	46.93
2001	48.06
2002	49.31
2003	50.75
2004	52.21
2005	53.67
2006	55.23
2007	56.71
2008	58.22
2009	59.87
2010	61.76
2011	63.41
2012	65.3
2013	67.24
2014	69.2
2015	71.16
2016	73.27