Year	Number of
1990	4.99
1991	4.84
1992	4.78
1993	4.81
1994	4.66
1995	4.33
1996	4.56
1997	4.3
1998	4.39
1999	4.27
2000	4.27
2001	3.79
2002	3.72
2003	3.61
2004	3.4
2005	3.24
2006	3.26
2007	3.14
2008	3.13
2009	3.1
2010	3.12
2011	3.04
2012	3.06
2013	3.06
2014	3.11
2015	3.03
2016	3.21