Year	Number
1992	11.20588
1993	10.40818
1994	10.01857
1995	9.77604
1996	10.09675
1997	10.25544
2000	11.18394
2001	11.50088
2002	10.39653
2004	10.26179
2005	9.90824
2006	9.70397
2007	9.45009
2008	9.15568
2009	8.94914
2010	8.83776
2011	8.56257
2012	8.31545
2013	8.10003
2014	8.07679
2015	7.88976
2016	7.68762
2017	7.80821