Year	Percent
1991	59.804
1992	58.293
1993	57.571
1994	58.531
1995	60.1
1996	60.468
1997	61.535
1998	64.272
1999	66.572
2000	68.311
2001	68.628
2002	67.665
2003	67.494
2004	67.958
2005	69.466
2006	70.107
2007	69.884
2008	67.36
2009	60.113
2010	57.411
2011	56.265
2012	56.06
2013	58.044
2014	59.393
2015	60.769
2016	61.682
2017	62.362
2018	62.192
2019	61.662
2020	61.248
2021	60.904
2022	60.598