Year	Percent
1990	80.843
1991	80.807
1992	80.737
1993	80.588
1994	80.582
1995	80.538
1996	80.499
1997	80.494
1998	80.426
1999	80.393
2000	80.356
2001	80.35
2002	80.354
2003	80.392
2004	80.431
2005	80.483
2006	80.581
2007	79.788
2008	78.937
2009	78.017
2010	77.023
2011	75.935
2012	75.998
2013	76.044
2014	76.078
2015	76.086
2016	76.07
2017	75.819
2018	75.559
2019	75.295
2020	75.029
2021	74.758
2022	74.487
2023	74.218
2024	73.957
2025	73.704
2026	73.453
2027	73.212
2028	72.977
2029	72.745
2030	72.514