Year	Percent
1991	76.526
1992	77.035
1993	76.864
1994	77.46
1995	77.349
1996	77.033
1997	70.961
1998	70.639
1999	70.356
2000	69.948
2001	69.415
2002	69.109
2003	68.692
2004	68.647
2005	68.475
2006	68.557
2007	68.906
2008	68.867
2009	68.812
2010	68.714
2011	68.596
2012	68.299
2013	67.957
2014	67.465
2015	67.293
2016	67.164
2017	67.28
2018	67.255
2019	67.222
2020	67.188
2021	67.156
2022	67.124