Year	Percent
1990	94.08
1991	93.933
1992	94.3
1993	93.934
1994	94.374
1995	93.858
1996	93.748
1997	93.8
1998	93.86
1999	93.107
2000	92.269
2001	91.338
2002	90.307
2003	89.169
2004	87.914
2005	86.536
2006	85.027
2007	83.382
2008	81.595
2009	79.663
2010	77.584
2011	75.358
2012	72.989
2013	70.48
2014	70.252
2015	70.134
2016	70.004
2017	69.75
2018	69.496
2019	69.243
2020	68.989
2021	68.735
2022	68.481
2023	68.228
2024	67.974
2025	67.72
2026	67.466
2027	67.213
2028	66.959
2029	66.705
2030	66.451