Year	Percent
1991	67.837
1992	67.137
1993	67.353
1994	64.78
1995	63.362
1996	62.123
1997	63.987
1998	64.361
1999	63.053
2000	63.15
2001	62.307
2002	61.154
2003	60.358
2004	59.182
2005	59.396
2006	59.27
2007	58.888
2008	58.25
2009	58.982
2010	57.761
2011	57.308
2012	57.001
2013	56.221
2014	55.619
2015	56.366
2016	57.392
2017	57.327
2018	57.264
2019	57.191
2020	57.11
2021	57.023
2022	56.932