Year	Percent
1990	79.325
1991	78.156
1992	76.671
1993	77.132
1994	76.837
1995	74.971
1996	75.903
1997	76.63
1998	77.619
1999	78.26
2000	76.963
2001	76.871
2002	76.823
2003	76.793
2004	76.75
2005	76.677
2006	76.701
2007	76.677
2008	76.592
2009	76.449
2010	76.318
2011	75.913
2012	75.949
2013	76.291
2014	75.403
2015	74.862
2016	74.374
2017	74.129
2018	73.855
2019	73.551
2020	73.224
2021	72.958
2022	72.681
2023	72.4
2024	72.135
2025	71.899
2026	71.767
2027	71.668
2028	71.588
2029	71.506
2030	71.412