Year	Number
1992	13.66056
1993	13.51259
1994	13.43836
1995	13.221
1996	13.21152
1997	13.40451
1998	13.68254
1999	13.6538
2000	13.25334
2001	13.38083
2002	13.55258
2003	13.54402
2004	13.39161
2005	13.22978
2006	13.25024
2007	13.15783
2008	13.18742
2009	13.06123
2010	13.11817
2011	13.1092
2012	13.03407
2013	13.56474
2014	13.39275
2015	13.31674
2016	13.25886
2017	13.28536
2018	13.35096