Year	Percent
1990	34.034
1991	33.94
1992	32.514
1993	26.603
1994	31.07
1995	30.753
1996	30.382
1997	28.603
1998	29.036
1999	29.769
2000	26.285
2001	26.835
2002	27.553
2003	26.213
2004	23.38
2005	23.305
2006	23.051
2007	23.111
2008	23.99
2009	25.479
2010	27.033
2011	28.322
2012	28.88
2013	30.103
2014	30.242
2015	31.474
2016	32.505
2017	32.369
2018	32.226
2019	32.073
2020	31.909
2021	31.735
2022	31.554
2023	31.364
2024	31.162
2025	30.947
2026	30.734
2027	30.508
2028	30.273
2029	30.033
2030	29.787