Year	Percent
1991	66.999
1992	66.486
1993	65.938
1994	65.344
1995	61.518
1996	72.597
1997	71.381
1998	70.005
1999	68.899
2000	68.55
2001	39.04
2002	38.781
2003	38.726
2004	36.086
2005	35.632
2006	37.089
2007	30.591
2008	28.998
2009	28.917
2010	28.994
2011	28.041
2012	27.503
2013	27.557
2014	26.985
2015	26.351
2016	26.083
2017	25.976
2018	25.958
2019	25.943
2020	25.928
2021	25.926
2022	25.932