Year	Percent
1991	24.742
1992	24.319
1993	23.891
1994	23.976
1995	24.563
1996	24.881
1997	24.328
1998	26.975
1999	27.613
2000	29.382
2001	28.035
2002	27.212
2003	27.757
2004	27.844
2005	29.357
2006	29.907
2007	30.355
2008	30.096
2009	29.089
2010	28.818
2011	29.286
2012	28.51
2013	28.649
2014	29.499
2015	29.937
2016	30.738
2017	30.797
2018	30.952
2019	31.04
2020	31.04
2021	31.086
2022	31.174