Year	Percent
1990	30.86
1991	30.59
1992	31.09
1993	27.42
1994	29.99
1995	32.97
1996	33.5
1997	31.49
1998	33.9
1999	33.82
2000	32.45
2001	30.45
2002	26.6
2003	25.31
2004	23.26
2005	22.14
2006	20.14
2007	18.71
2008	19.36
2009	19.46
2010	19.81
2011	20.75
2012	20.14
2013	20.49
2014	19.32
2015	19.94
2016	19.9
2017	19.56
2018	19.22
2019	18.88
2020	18.541
2021	18.201
2022	17.861
2023	17.521
2024	17.181
2025	16.841
2026	16.502
2027	16.162
2028	15.822
2029	15.482
2030	15.142