Year	Number
1992	12.43306
1993	12.25316
1994	12.39555
1995	12.64766
1996	12.59239
1997	12.49706
1998	12.54894
1999	12.70012
2000	12.60632
2001	12.41534
2002	12.43107
2003	12.46843
2004	12.26662
2005	12.04845
2006	11.9017
2007	11.6585
2008	11.556
2009	11.58776
2010	11.60218
2011	11.48117
2012	11.57968
2013	11.8083
2014	11.61379
2015	11.49219
2016	11.38812
2017	11.5413
2018	11.55706