Year	Number of
1990	46.27
1991	48.08
1992	48.01
1993	49.62
1994	51.32
1995	51.33
1996	51.56
1997	52.07
1998	52.73
1999	53.87
2000	55.93
2001	58.24
2002	60.83
2003	63.03
2004	66.98
2005	68.81
2006	69.33
2007	73.64
2008	75.56
2009	79.04
2010	81.17
2011	82.13
2012	83.88
2013	86.61
2014	87.58
2015	89.2
2016	91.64