Year	Percent
1990	79.809
1991	79.613
1992	79.124
1993	79.116
1994	78.861
1995	78.679
1996	78.884
1997	79.285
1998	79.512
1999	79.852
2000	80.949
2001	81.621
2002	81.976
2003	81.869
2004	81.803
2005	81.683
2006	81.557
2007	81.387
2008	81.2
2009	81.566
2010	81.355
2011	80.812
2012	80.641
2013	80.549
2014	80.54
2015	80.426
2016	80.373
2017	80.337
2018	80.307
2019	80.27
2020	80.223
2021	80.187
2022	80.143
2023	80.097
2024	80.06
2025	80.038
2026	80.045
2027	80.063
2028	80.09
2029	80.121
2030	80.156