Year	Number of
1990	10.85
1991	10.44
1992	10.36
1993	10.23
1994	10.17
1995	9.96
1996	10.49
1997	9.41
1998	9.29
1999	10.42
2000	9.96
2001	8.91
2002	9.15
2003	9.09
2004	9.05
2005	9.89
2006	10.16
2007	9.66
2008	9.85
2009	10.18
2010	10.4
2011	10.28
2012	10.29
2013	11.44
2014	11.29
2015	11.47
2016	11.46