Year	Number of
1990	56.41
1991	56.67
1992	57.17
1993	57.63
1994	58.02
1995	58.32
1996	58.54
1997	58.7
1998	58.91
1999	59.55
2000	60.59
2001	59.44
2002	60.1
2003	59.23
2004	58.63
2005	58.33
2006	59.55
2007	59.07
2008	58.31
2009	57.3
2010	57.94
2011	58.05
2012	60.44
2013	62.45
2014	64.47
2015	66.45
2016	68.35