Year	Percent
1990	91.483
1991	91.569
1992	91.589
1993	91.462
1994	91.274
1995	91.069
1996	91.059
1997	91.095
1998	91.138
1999	91.287
2000	91.45
2001	91.567
2002	91.676
2003	91.762
2004	91.878
2005	91.954
2006	92.031
2007	92.107
2008	92.135
2009	92.207
2010	92.197
2011	92.209
2012	92.142
2013	92.097
2014	92.032
2015	91.972
2016	91.873
2017	91.841
2018	91.818
2019	91.807
2020	91.809
2021	91.825
2022	91.853
2023	91.894
2024	91.95
2025	92.021
2026	92.104
2027	92.198
2028	92.301
2029	92.409
2030	92.52