Year	Number of
1990	49.01
1991	49.28
1992	51.11
1993	51.71
1994	54.7
1995	55.33
1996	56.69
1997	59.82
1998	62.64
1999	64.02
2000	64.92
2001	65.41
2002	67.15
2003	67.8
2004	69.57
2005	69.93
2006	70.9
2007	71.01
2008	70.25
2009	68.94
2010	68.1
2011	67.92
2012	67.78
2013	67.47
2014	66.58
2015	65.09
2016	64.43