Year	Percent
1990	27.683
1991	28.81
1992	29.122
1993	29.438
1994	30.066
1995	29.927
1996	30.577
1997	31.04
1998	31.486
1999	31.96
2000	32.558
2001	32.906
2002	33.284
2003	34.254
2004	34.814
2005	35.687
2006	36.187
2007	36.632
2008	36.829
2009	36.803
2010	37.133
2011	33.094
2012	35.527
2013	33.839
2014	32.381
2015	32.228
2016	32.256
2017	32.258
2018	32.257
2019	32.26
2020	32.27
2021	32.288
2022	32.313
2023	32.346
2024	32.388
2025	32.439
2026	32.503
2027	32.577
2028	32.663
2029	32.763
2030	32.878