Year	Percent
1990	33.955
1991	33.522
1992	32.511
1993	32.983
1994	32.336
1995	31.858
1996	31.532
1997	30.832
1998	29.763
1999	29.43
2000	29.402
2001	29.374
2002	29.346
2003	29.318
2004	29.29
2005	29.262
2006	29.234
2007	29.206
2008	29.178
2009	29.15
2010	29.122
2011	29.094
2012	29.066
2013	29.038
2014	29.01
2015	32.095
2016	33.797
2017	33.66
2018	33.523
2019	33.386
2020	33.249
2021	33.112
2022	32.974
2023	32.837
2024	32.7
2025	32.563
2026	32.426
2027	32.288
2028	32.151
2029	32.014
2030	31.877