Year	Percent
1990	79.827
1991	80.074
1992	79.771
1993	79.691
1994	79.423
1995	79.313
1996	78.982
1997	78.243
1998	77.487
1999	76.734
2000	76.001
2001	75.58
2002	75.178
2003	74.764
2004	74.297
2005	73.756
2006	72.914
2007	72.012
2008	72.698
2009	73.323
2010	73.921
2011	74.519
2012	75.074
2013	75.572
2014	75.994
2015	75.676
2016	75.556
2017	75.402
2018	75.214
2019	74.989
2020	74.725
2021	74.448
2022	74.14
2023	73.82
2024	73.518
2025	73.258
2026	73.052
2027	72.889
2028	72.761
2029	72.657
2030	72.572