Year	Percent
1990	79.941
1991	79.835
1992	79.747
1993	79.614
1994	79.783
1995	79.895
1996	79.93
1997	80.015
1998	80.206
1999	80.19
2000	80.31
2001	80.396
2002	80.514
2003	80.523
2004	80.566
2005	80.614
2006	80.628
2007	80.678
2008	80.621
2009	80.413
2010	80.349
2011	80.358
2012	80.356
2013	80.35
2014	80.372
2015	80.43
2016	80.448
2017	80.475
2018	80.509
2019	80.545
2020	80.579
2021	80.608
2022	80.632
2023	80.656
2024	80.694
2025	80.751
2026	80.823
2027	80.912
2028	81.009
2029	81.098
2030	81.17