Year	Percent
1990	37.976
1991	37.327
1992	36.517
1993	34.847
1994	32.741
1995	31.02
1996	29.576
1997	30.726
1998	29.642
1999	30.332
2000	30.765
2001	30.756
2002	31.29
2003	31.985
2004	31.41
2005	30.147
2006	28.913
2007	27.71
2008	24.891
2009	22.3
2010	21.085
2011	22.216
2012	23.737
2013	25.802
2014	27.258
2015	28.287
2016	28.895
2017	28.316
2018	27.736
2019	27.157
2020	26.578
2021	25.998
2022	25.419
2023	24.84
2024	24.26
2025	23.681
2026	23.102
2027	22.522
2028	21.943
2029	21.364
2030	20.784