Year	Number of
1990	7.97
1991	8.29
1992	8.61
1993	8.99
1994	8.78
1995	9.01
1996	8.61
1997	8.9
1998	9.38
1999	10.43
2000	10.7
2001	11.55
2002	11.85
2003	11.85
2004	11.8
2005	10.91
2006	11.68
2007	11.75
2008	11.38
2009	10.9
2010	10.25
2011	10
2012	9.77
2013	8.96
2014	8.45
2015	8.53
2016	8.52