Year	Number
1992	13.26197
1993	13.10615
1994	13.03213
1995	12.80911
1996	12.75302
1997	12.79727
1998	13.28487
1999	13.10187
2000	12.80876
2001	12.84228
2002	12.91797
2003	12.8877
2004	12.83578
2005	12.8252
2006	12.82509
2007	12.68034
2008	12.76176
2009	12.58991
2010	12.56685
2011	12.56088
2012	12.50398
2013	12.73038
2014	12.87262
2015	12.81886
2016	12.70371
2017	12.6585
2018	12.73081