Year	Percent
1991	51.963
1992	52.658
1993	53.119
1994	52.265
1995	50.763
1996	52.175
1997	52.515
1998	53.493
1999	52.979
2000	53.611
2001	54.09
2002	54.038
2003	54.381
2004	53.731
2005	52.96
2006	55.173
2007	56.194
2008	54.939
2009	55.346
2010	55.452
2011	56.935
2012	57.751
2013	59.022
2014	60.513
2015	60.853
2016	62.319
2017	62.52
2018	62.878
2019	63.042
2020	63.368
2021	63.737
2022	64.106