Year	Percent
1990	21.796
1991	21.897
1992	21.829
1993	21.683
1994	21.517
1995	21.191
1996	20.857
1997	20.535
1998	20.197
1999	19.782
2000	19.36
2001	19.036
2002	18.637
2003	18.189
2004	17.841
2005	17.453
2006	16.987
2007	16.594
2008	16.213
2009	15.928
2010	15.69
2011	15.485
2012	15.222
2013	14.927
2014	14.722
2015	14.57
2016	14.543
2017	14.356
2018	14.17
2019	13.983
2020	13.797
2021	13.61
2022	13.424
2023	13.237
2024	13.051
2025	12.864
2026	12.678
2027	12.491
2028	12.305
2029	12.118
2030	11.932