Year	Percent
1991	76.248
1992	76.598
1993	76.415
1994	75.839
1995	75.451
1996	75.36
1997	75.373
1998	74.331
1999	73.419
2000	72.877
2001	71.992
2002	71.021
2003	70.483
2004	70.174
2005	70.195
2006	70.173
2007	70.646
2008	70.278
2009	68.785
2010	68.206
2011	67.984
2012	67.711
2013	67.819
2014	68.142
2015	68.241
2016	68.555
2017	68.458
2018	68.405
2019	68.138
2020	67.749
2021	67.386
2022	67.054