Year	Percent
1990	73.864
1991	73.278
1992	72.791
1993	72.107
1994	71.382
1995	73.044
1996	72.858
1997	73.13
1998	71.741
1999	72.611
2000	71.709
2001	71.222
2002	72.129
2003	71.64
2004	71.852
2005	71.41
2006	71.527
2007	71.027
2008	71.207
2009	70.182
2010	69.069
2011	68.408
2012	67.353
2013	66.159
2014	66.262
2015	66.441
2016	67.392
2017	67.181
2018	67.022
2019	66.869
2020	66.691
2021	66.487
2022	66.267
2023	66.034
2024	65.798
2025	65.563
2026	65.329
2027	65.103
2028	64.88
2029	64.653
2030	64.418