Year	Percent
1990	76.871
1991	76.599
1992	76.325
1993	76.05
1994	75.78
1995	75.515
1996	75.179
1997	75.107
1998	75.035
1999	74.967
2000	74.906
2001	74.877
2002	74.855
2003	74.824
2004	74.765
2005	74.668
2006	74.594
2007	74.45
2008	74.241
2009	73.981
2010	73.714
2011	73.271
2012	72.718
2013	72.276
2014	71.843
2015	71.373
2016	70.993
2017	70.919
2018	70.861
2019	70.821
2020	70.8
2021	70.805
2022	70.832
2023	70.876
2024	70.938
2025	71.013
2026	71.097
2027	71.192
2028	71.296
2029	71.402
2030	71.508