Year	Percent
1990	83.53
1991	83.498
1992	83.51
1993	82.72
1994	81.901
1995	81.052
1996	80.173
1997	79.263
1998	78.323
1999	77.353
2000	76.352
2001	75.321
2002	74.26
2003	73.665
2004	73.061
2005	72.449
2006	71.828
2007	71.199
2008	70.561
2009	69.915
2010	69.262
2011	68.6
2012	68.405
2013	68.066
2014	67.752
2015	67.65
2016	67.472
2017	67.215
2018	66.958
2019	66.702
2020	66.445
2021	66.188
2022	65.931
2023	65.674
2024	65.417
2025	65.161
2026	64.904
2027	64.647
2028	64.39
2029	64.133
2030	63.876