Year	Number of
1990	51.92
1991	49.68
1992	52.05
1993	52.58
1994	52.31
1995	50.84
1996	53.3
1997	54.22
1998	53.86
1999	53.48
2000	55.1
2001	56.62
2002	55.28
2003	55.83
2004	54.56
2005	56.11
2006	59.21
2007	60.86
2008	63.2
2009	62.24
2010	62.72
2011	62.9
2012	63.58
2013	62.73
2014	65.13
2015	67.06
2016	69.39