Year	Number
1993	8.89418
1994	8.81186
1995	8.15073
1997	8.21592
1999	11.58917
2000	11.62031
2001	11.57255
2002	11.34407
2003	11.38761
2004	11.31689
2005	11.32372
2006	11.61474
2007	11.34105
2008	11.12634
2009	11.66414
2010	15.59747
2011	15.03454
2012	13.98772
2013	13.38133
2014	12.8823
2015	12.55536
2016	12.39395
2017	12.28346