Year	Number of
1990	5.93
1991	5.06
1992	5.37
1993	5.84
1994	5.86
1995	4.85
1996	5.51
1997	5.96
1998	5.46
1999	5.06
2000	4.83
2001	4.6
2002	3.86
2003	3.56
2004	3.54
2005	3.2
2006	2.89
2007	3.41
2008	3.25
2009	3.35
2010	3.63
2011	3.65
2012	3.67
2013	3.95
2014	3.88
2015	4.06
2016	4.07