Year	Percent
1990	27.68
1991	27.929
1992	28.18
1993	28.432
1994	28.685
1995	28.94
1996	29.196
1997	29.453
1998	29.711
1999	29.971
2000	30.233
2001	30.495
2002	29.355
2003	29.935
2004	28.315
2005	29.104
2006	29.905
2007	26.895
2008	26.85
2009	26.805
2010	24.851
2011	22.995
2012	23.19
2013	23.09
2014	22.4
2015	22.45
2016	21.99
2017	21.737
2018	21.484
2019	21.231
2020	20.978
2021	20.725
2022	20.472
2023	20.219
2024	19.966
2025	19.713
2026	19.46
2027	19.207
2028	18.954
2029	18.701
2030	18.448