Year	Percent
1990	55.946
1991	56.101
1992	56.227
1993	56.12
1994	56.225
1995	56.247
1996	56.338
1997	56.427
1998	56.504
1999	56.501
2000	56.485
2001	56.621
2002	56.705
2003	56.81
2004	57.02
2005	57.09
2006	57.08
2007	57.057
2008	57.004
2009	56.937
2010	56.928
2011	56.849
2012	56.819
2013	56.745
2014	56.663
2015	56.523
2016	56.349
2017	56.363
2018	56.376
2019	56.39
2020	56.403
2021	56.417
2022	56.431
2023	56.444
2024	56.458
2025	56.471
2026	56.485
2027	56.499
2028	56.512
2029	56.526
2030	56.539