Year	Percent
1990	23.58
1991	23.522
1992	23.465
1993	23.407
1994	23.35
1995	22.04
1996	20.783
1997	19.58
1998	18.43
1999	17.832
2000	17.249
2001	16.681
2002	16.128
2003	15.59
2004	17.26
2005	17.181
2006	17.147
2007	17.048
2008	16.827
2009	16.404
2010	16.146
2011	16.123
2012	15.971
2013	15.89
2014	15.863
2015	15.922
2016	16.061
2017	15.968
2018	15.875
2019	15.781
2020	15.688
2021	15.595
2022	15.501
2023	15.408
2024	15.315
2025	15.221
2026	15.128
2027	15.035
2028	14.941
2029	14.848
2030	14.755