Year	%
1990	22.9166666666667
1991	24.3697478991597
1992	25.813221406086
1993	27.2474513438369
1994	28.5123966942149
1995	29.7096053611318
1996	30.5298013245033
1997	31.1581422692534
1998	31.5817130846033
1999	31.9279962103269
2000	32.2121604139715
2001	32.4742268041237
2002	32.7579875137716
2003	32.9553264604811
2004	33.0851408222726
2005	33.180006133088
2006	33.1388564760793
2007	33.0277777777778
2008	32.9614873837981
2009	32.9246487867178
2010	32.8535980148883
2011	32.7781800627565
2012	32.6904985888993
2013	32.6061997703789
2014	32.5325550067355
2015	32.4752475247525
2016	32.4184136589583
2017	32.3904721395151
2018	32.3480083857442
2019	32.3328503415442
2020	32.3095823095823
2021	32.3595049705823
2022	32.4269889224572