Year	Percent
1991	60.587
1992	60.555
1993	60.518
1994	60.489
1995	60.474
1996	60.417
1997	60.318
1998	60.029
1999	59.839
2000	59.859
2001	59.843
2002	59.85
2003	59.839
2004	59.842
2005	59.866
2006	59.918
2007	59.974
2008	60.053
2009	60.15
2010	60.265
2011	60.399
2012	60.557
2013	60.65
2014	60.797
2015	60.914
2016	61.045
2017	61.183
2018	61.312
2019	61.433
2020	61.543
2021	61.638
2022	61.725