Year	Percent
1990	21.934
1991	20.446
1992	20.021
1993	20.776
1994	19.96
1995	20.205
1996	18.887
1997	17.013
1998	16.593
1999	16.239
2000	15.891
2001	16.745
2002	17.173
2003	16.867
2004	16.925
2005	17.921
2006	18.27
2007	18.199
2008	19.552
2009	19.871
2010	21.167
2011	22.923
2012	24.804
2013	26.547
2014	26.974
2015	26.897
2016	29.543
2017	29.678
2018	29.813
2019	29.948
2020	30.083
2021	30.218
2022	30.353
2023	30.488
2024	30.623
2025	30.758
2026	30.893
2027	31.028
2028	31.163
2029	31.298
2030	31.433