Year	Number
1992	14.3608
1993	14.21624
1994	14.32661
1995	14.60773
1996	14.64095
1997	14.4895
1998	14.29477
1999	14.37277
2000	14.15716
2001	14.00823
2002	13.62991
2003	13.53357
2004	13.28354
2005	13.1454
2006	12.98197
2007	12.78714
2008	12.60329
2009	12.57089
2010	12.46551
2011	12.67324
2012	12.76338
2013	12.78694
2014	12.6178
2015	12.50769
2016	12.39064
2017	12.4197
2018	12.4354