Year	Percent
1990	80.274
1991	80.226
1992	80.175
1993	80.13
1994	80.085
1995	80.064
1996	79.891
1997	79.799
1998	79.792
1999	79.891
2000	80.061
2001	80.054
2002	80.156
2003	80.347
2004	80.579
2005	80.823
2006	80.84
2007	80.864
2008	80.928
2009	81.045
2010	81.174
2011	81.216
2012	81.285
2013	81.384
2014	81.501
2015	81.623
2016	81.668
2017	81.709
2018	81.762
2019	81.835
2020	81.926
2021	81.926
2022	81.947
2023	81.98
2024	82.006
2025	82.009
2026	81.898
2027	81.773
2028	81.653
2029	81.56
2030	81.504