Year	%
1990	0
1991	50
1992	25
1993	28.5714285714286
1994	27.2727272727273
1995	27.7777777777778
1996	26.6666666666667
1997	29.1666666666667
1998	28.2051282051282
1999	29.5081967213115
2000	29.6296296296296
2001	30.4195804195804
2002	30.607476635514
2003	30.7073954983923
2004	30.8924485125858
2005	30.9243697478992
2006	30.9859154929578
2007	31.0920121334681
2008	31.1725846407927
2009	31.2630117973629
2010	31.2963512310887
2011	31.3212435233161
2012	31.3075506445672
2013	31.3253012048193
2014	31.4888762122076
2015	31.6408995080815
2016	31.7839607201309
2017	31.9116293341516
2018	32.0179242555652
2019	32.1018062397373
2020	32.1502860114405
2021	32.2040208488459
2022	32.2457728030483