Year	Percent
1991	41.843
1992	41.783
1993	42.473
1994	41.579
1995	41.393
1996	41.03
1997	40.769
1998	42.216
1999	40.709
2000	39.539
2001	38.674
2002	37.618
2003	35.628
2004	34.758
2005	34.278
2006	33.671
2007	32.722
2008	31.896
2009	30.359
2010	28.889
2011	28.323
2012	27.927
2013	27.313
2014	26.632
2015	25.754
2016	25.065
2017	25.023
2018	25.005
2019	24.987
2020	24.969
2021	24.952
2022	24.935