Year	Percent
1990	50.537
1991	50.554
1992	50.627
1993	50.706
1994	50.789
1995	50.876
1996	50.981
1997	51.058
1998	51.145
1999	51.147
2000	51.204
2001	51.266
2002	51.369
2003	51.49
2004	51.599
2005	51.641
2006	51.775
2007	51.888
2008	51.958
2009	51.769
2010	51.757
2011	51.844
2012	51.913
2013	51.989
2014	51.992
2015	52.075
2016	52.191
2017	52.316
2018	52.463
2019	52.609
2020	52.742
2021	52.876
2022	52.994
2023	53.102
2024	53.211
2025	53.328
2026	53.467
2027	53.615
2028	53.761
2029	53.887
2030	53.982