Year	Percent
1990	49.106
1991	49.522
1992	49.866
1993	50.03
1994	50.149
1995	50.021
1996	50.074
1997	49.954
1998	49.832
1999	49.617
2000	49.457
2001	49.355
2002	49.09
2003	49.083
2004	48.975
2005	48.814
2006	48.766
2007	48.749
2008	48.478
2009	48.585
2010	48.507
2011	48.324
2012	48.101
2013	47.973
2014	47.972
2015	47.987
2016	47.615
2017	47.527
2018	47.439
2019	47.352
2020	47.264
2021	47.176
2022	47.088
2023	47.001
2024	46.913
2025	46.825
2026	46.737
2027	46.65
2028	46.562
2029	46.474
2030	46.386