Year	Number
1992	15.11859
1993	15.28538
1994	15.3556
1995	14.4091
1996	14.44125
1997	14.43236
1998	14.4224
1999	14.17045
2000	13.84615
2001	14.37622
2002	15.1282
2003	15.17738
2004	15.71462
2005	15.70629
2006	15.40086
2007	15.33213
2008	15.24719
2009	14.54433
2010	14.47947
2011	14.72191
2012	14.70378
2013	14.70568
2014	14.75868
2015	14.64911
2016	14.63235
2017	14.68479
2018	14.67917