Year	Number of
1990	5.72
1991	5.87
1992	5.9
1993	5.71
1994	5.86
1995	5.67
1996	5.44
1997	5.15
1998	5.1
1999	4.97
2000	4.85
2001	4.68
2002	4.74
2003	4.67
2004	4.53
2005	4.35
2006	4.35
2007	4.15
2008	4.23
2009	4.31
2010	4.38
2011	4.49
2012	4.62
2013	4.82
2014	5
2015	5.06
2016	5.26