Year	Percent
1990	76.218
1991	76.285
1992	75.479
1993	74.65
1994	73.792
1995	72.908
1996	71.988
1997	71.038
1998	70.063
1999	69.06
2000	68.027
2001	66.957
2002	65.862
2003	64.746
2004	63.602
2005	62.435
2006	61.228
2007	60.849
2008	60.47
2009	60.093
2010	59.718
2011	59.341
2012	58.971
2013	58.607
2014	58.249
2015	58.306
2016	58.367
2017	58.148
2018	57.925
2019	57.698
2020	57.465
2021	57.229
2022	56.991
2023	56.753
2024	56.519
2025	56.293
2026	56.076
2027	55.867
2028	55.663
2029	55.461
2030	55.261