Year	Percent
1991	68.887
1992	69.235
1993	69.605
1994	69.498
1995	68.608
1996	68.495
1997	67.73
1998	67.459
1999	66.942
2000	66.411
2001	66.713
2002	66.263
2003	65.686
2004	65.549
2005	65.466
2006	64.806
2007	63.436
2008	63.208
2009	63.101
2010	63.15
2011	62.476
2012	62.849
2013	62.292
2014	61.766
2015	61.639
2016	61.236
2017	61.015
2018	60.954
2019	60.885
2020	60.81
2021	60.738
2022	60.665