Year	Number of
1990	53.86
1991	51.37
1992	53.64
1993	54.1
1994	53.67
1995	52.09
1996	54.41
1997	55.1
1998	54.54
1999	54.18
2000	55.99
2001	57.68
2002	56.42
2003	57.03
2004	55.73
2005	57.13
2006	59.87
2007	60.83
2008	62.48
2009	61.04
2010	61.04
2011	60.8
2012	61.01
2013	59.92
2014	61.83
2015	63.12
2016	64.74