Year	Percent
1990	37.617
1991	37.707
1992	37.696
1993	37.686
1994	37.635
1995	37.601
1996	37.676
1997	37.685
1998	37.681
1999	37.667
2000	37.602
2001	37.639
2002	37.636
2003	37.647
2004	37.619
2005	37.616
2006	37.65
2007	36.762
2008	35.883
2009	35.013
2010	34.153
2011	33.303
2012	32.464
2013	31.636
2014	30.82
2015	30.755
2016	30.702
2017	30.475
2018	30.249
2019	30.023
2020	29.796
2021	29.57
2022	29.344
2023	29.117
2024	28.891
2025	28.665
2026	28.438
2027	28.212
2028	27.986
2029	27.759
2030	27.533