Year	Percent
1991	69.768
1992	70.023
1993	69.968
1994	69.838
1995	69.534
1996	69.308
1997	69.061
1998	68.693
1999	68.393
2000	68.15
2001	67.381
2002	66.619
2003	65.818
2004	64.984
2005	64.325
2006	63.731
2007	63.295
2008	62.433
2009	61.951
2010	61.43
2011	61.122
2012	60.826
2013	60.563
2014	60.264
2015	59.936
2016	59.471
2017	58.883
2018	58.225
2019	57.543
2020	56.868
2021	56.209
2022	55.556