Year	Percent
1991	57.481
1992	57.672
1993	57.065
1994	58.213
1995	58.55
1996	59.65
1997	60.807
1998	61.02
1999	62.001
2000	60.368
2001	62.564
2002	63.578
2003	64.757
2004	65.938
2005	66.565
2006	66.415
2007	64.974
2008	66.717
2009	66.695
2010	68.038
2011	68.264
2012	68.297
2013	67.921
2014	68.509
2015	66.254
2016	65.572
2017	66.408
2018	66.534
2019	66.872
2020	67.193
2021	67.484
2022	67.858