Year	Percent
1990	90.647
1991	90.385
1992	90.133
1993	89.957
1994	89.742
1995	89.572
1996	89.444
1997	89.352
1998	89.316
1999	89.291
2000	89.444
2001	89.562
2002	89.672
2003	89.777
2004	89.876
2005	89.968
2006	90.057
2007	90.144
2008	90.232
2009	90.321
2010	90.41
2011	90.497
2012	90.588
2013	90.684
2014	90.469
2015	90.363
2016	90.295
2017	90.391
2018	90.487
2019	90.58
2020	90.668
2021	90.754
2022	90.836
2023	90.915
2024	90.995
2025	91.076
2026	91.161
2027	91.246
2028	91.33
2029	91.409
2030	91.48
