Year	Number of
1990	60.54
1991	60.04
1992	60.52
1993	60.81
1994	62.08
1995	62.31
1996	61.17
1997	59.63
1998	58.72
1999	57.08
2000	56.73
2001	56.7
2002	55.95
2003	55.76
2004	56.63
2005	56.9
2006	57.99
2007	59.87
2008	62.1
2009	64.79
2010	67.39
2011	71
2012	75.25
2013	80.2
2014	84.91
2015	90.1
2016	95.77