Year	Percent
1990	81.631
1991	81.7
1992	81.817
1993	81.87
1994	81.867
1995	81.713
1996	81.609
1997	81.506
1998	81.359
1999	81.147
2000	80.948
2001	80.753
2002	80.533
2003	80.354
2004	80.127
2005	79.87
2006	79.831
2007	79.542
2008	79.384
2009	79.238
2010	79.049
2011	78.8
2012	76.531
2013	74.1
2014	71.51
2015	71.255
2016	70.995
2017	70.789
2018	70.583
2019	70.376
2020	70.17
2021	69.964
2022	69.758
2023	69.552
2024	69.346
2025	69.14
2026	68.933
2027	68.727
2028	68.521
2029	68.315
2030	68.109