Year	Number of
1990	8.93
1991	8.86
1992	9.3
1993	9.7
1994	9.77
1995	9.55
1996	9.46
1997	9.55
1998	9.89
1999	10.39
2000	10.81
2001	11.14
2002	11.49
2003	11.51
2004	11.43
2005	11.2
2006	11.13
2007	10.98
2008	10.85
2009	10.78
2010	10.83
2011	10.84
2012	10.96
2013	11.21
2014	11.58
2015	11.8
2016	12