Year	Percent
1990	51.993
1991	51.796
1992	51.813
1993	51.847
1994	51.837
1995	51.802
1996	52.197
1997	52.626
1998	52.695
1999	53.216
2000	53.554
2001	53.374
2002	53.949
2003	53.908
2004	54.308
2005	54.713
2006	55.128
2007	54.946
2008	55.269
2009	55.488
2010	55.455
2011	55.519
2012	55.78
2013	56.144
2014	56.425
2015	56.553
2016	56.774
2017	56.816
2018	56.857
2019	56.875
2020	56.851
2021	56.795
2022	56.708
2023	56.595
2024	56.471
2025	56.345
2026	56.236
2027	56.132
2028	56.035
2029	55.947
2030	55.868