Year	Number of
1990	86.02
1991	83.66
1992	84.1
1993	86.49
1994	86.56
1995	89.42
1996	89.28
1997	88.62
1998	88.56
1999	85.07
2000	79.54
2001	75.17
2002	70.22
2003	68.84
2004	66.58
2005	64.12
2006	63.07
2007	63.46
2008	64.01
2009	63.91
2010	62.92
2011	63.44
2012	64.21
2013	65.24
2014	66.49
2015	67.93
2016	69.65