Year	%
1990	22.6606155155297
1991	21.9764630415474
1992	21.353247391586
1993	20.7558431766776
1994	20.1709987699381
1995	19.5956809114547
1996	19.1839161111761
1997	18.9104547228542
1998	18.724564089161
1999	18.6065121412804
2000	18.5404967553448
2001	18.5137674351377
2002	18.4750239302301
2003	18.4727837986534
2004	18.4682476195391
2005	18.4807592810918
2006	18.5076572173346
2007	18.5012208511545
2008	18.4993260204535
2009	18.4831254877602
2010	18.4229890096127
2011	18.3395624045494
2012	18.2689767108293
2013	18.1833049606375
2014	18.0880495798994
2015	17.9966615802331
2016	17.9146979412757
2017	17.851292224534
2018	17.7959771285771
2019	17.7508511916683
2020	17.7159473927698
2021	17.6759528868603
2022	17.6531393317675