Year	Percent
1990	77.789
1991	77.882
1992	78.03
1993	78.154
1994	78.251
1995	78.296
1996	78.335
1997	78.342
1998	78.328
1999	78.302
2000	78.275
2001	78.275
2002	78.274
2003	78.279
2004	78.297
2005	78.341
2006	78.42
2007	78.524
2008	78.66
2009	78.837
2010	79.058
2011	79.326
2012	79.629
2013	79.958
2014	80.296
2015	80.627
2016	80.958
2017	81.283
2018	81.573
2019	81.785
2020	81.896
2021	81.924
2022	81.855
2023	81.721
2024	81.575
2025	81.446
2026	81.342
2027	81.254
2028	81.179
2029	81.114
2030	81.057
