Year	Percent
1991	74.889
1992	75.332
1993	75.821
1994	76.064
1995	76.044
1996	75.646
1997	74.937
1998	74.354
1999	73.229
2000	70.83
2001	69.639
2002	68.132
2003	66.232
2004	64.236
2005	62.084
2006	60.536
2007	58.241
2008	56.924
2009	55.621
2010	54.596
2011	53.915
2012	53.215
2013	52.589
2014	51.905
2015	51.41
2016	51.085
2017	50.786
2018	50.573
2019	50.389
2020	50.199
2021	50.12
2022	50.049