Year	Percent
1990	30.517
1991	30.969
1992	31.569
1993	33.705
1994	33.432
1995	33.179
1996	33.806
1997	34.842
1998	34.765
1999	36.331
2000	34.753
2001	35.481
2002	36.215
2003	36.429
2004	36.091
2005	36.901
2006	37.986
2007	37.372
2008	36.555
2009	36.055
2010	35.562
2011	35.084
2012	34.619
2013	34.159
2014	33.701
2015	33.245
2016	33.247
2017	33.196
2018	33.141
2019	33.077
2020	32.997
2021	32.927
2022	32.847
2023	32.755
2024	32.654
2025	32.547
2026	32.463
2027	32.376
2028	32.281
2029	32.169
2030	32.034