Year	Number of
1990	42.1
1991	43.71
1992	45.51
1993	47.01
1994	48.52
1995	50.24
1996	49.51
1997	48.96
1998	48.45
1999	48.04
2000	47.64
2001	49.45
2002	51.46
2003	53.57
2004	55.68
2005	58.02
2006	60.56
2007	63.2
2008	66.01
2009	68.95
2010	72.09
2011	72.65
2012	73.2
2013	73.64
2014	74.54
2015	75.51
2016	76.6