Year	Percent
1990	69.551
1991	69.548
1992	69.473
1993	69.451
1994	69.442
1995	69.416
1996	69.392
1997	69.356
1998	69.372
1999	69.323
2000	69.279
2001	69.306
2002	69.308
2003	69.327
2004	69.307
2005	69.314
2006	69.324
2007	69.313
2008	69.342
2009	69.291
2010	69.297
2011	69.251
2012	69.266
2013	69.231
2014	69.207
2015	69.158
2016	69.119
2017	69.071
2018	69.027
2019	68.987
2020	68.952
2021	68.922
2022	68.897
2023	68.876
2024	68.86
2025	68.849
2026	68.842
2027	68.839
2028	68.84
2029	68.843
2030	68.847