Year	Percent
1990	45.78
1991	46.209
1992	47.146
1993	48.143
1994	49.214
1995	50.362
1996	51.299
1997	52.336
1998	53.484
1999	54.679
2000	55.839
2001	56.228
2002	56.154
2003	56.198
2004	56.376
2005	56.644
2006	56.818
2007	57.017
2008	57.284
2009	57.633
2010	58.043
2011	58.49
2012	58.909
2013	59.314
2014	59.718
2015	59.398
2016	59.03
2017	59.025
2018	59.003
2019	58.979
2020	58.959
2021	58.956
2022	58.962
2023	58.958
2024	58.91
2025	58.8
2026	58.648
2027	58.443
2028	58.199
2029	57.942
2030	57.686