Year	%
1992	50.3832919408007
1993	50.8274582791732
1994	51.0431293989386
1995	51.0938415555909
1996	51.8336576210807
1997	52.0040988983947
1998	52.9171785546199
1999	53.0401485177703
2000	53.058286161937
2001	52.9734126964867
2002	53.0530565766884
2003	53.3932537866996
2004	53.350065786063
2005	53.8687954584712
2006	53.7089089459657
2007	53.7827383836285
2008	53.731923276471
2009	53.7212363682403
2010	53.6858238174284
2011	53.6939672736293
2012	53.7248892155004
2013	53.8184986320832
2014	54.0031200401806
2015	54.2087559127015
2016	54.334211934412
2017	54.4870318243732
2018	54.724626588709