Year	Percent
1990	68.133
1991	68.116
1992	68.028
1993	67.995
1994	67.975
1995	67.939
1996	67.905
1997	67.862
1998	67.874
1999	67.82
2000	67.77
2001	67.79
2002	67.785
2003	67.798
2004	67.771
2005	67.77
2006	67.767
2007	67.744
2008	67.763
2009	67.705
2010	67.707
2011	67.649
2012	67.655
2013	67.615
2014	67.59
2015	67.545
2016	67.515
2017	67.485
2018	67.461
2019	67.44
2020	67.421
2021	67.404
2022	67.391
2023	67.382
2024	67.376
2025	67.374
2026	67.374
2027	67.377
2028	67.384
2029	67.393
2030	67.403