Year	Percent
1990	78.9
1991	78.36
1992	77.81
1993	77.25
1994	76.68
1995	76.1
1996	75.556
1997	75.005
1998	74.445
1999	73.876
2000	73.3
2001	73.2
2002	73.101
2003	73.001
2004	72.9
2005	72.8
2006	72.77
2007	72.691
2008	72.723
2009	72.653
2010	72.978
2011	72.799
2012	72.734
2013	72.607
2014	72.542
2015	72.548
2016	72.54
2017	72.477
2018	72.415
2019	72.352
2020	72.289
2021	72.226
2022	72.164
2023	72.101
2024	72.038
2025	71.975
2026	71.913
2027	71.85
2028	71.787
2029	71.725
2030	71.662