Year	Percent
1990	33.48
1991	32.864
1992	31.331
1993	31.405
1994	31.336
1995	29.5
1996	29.348
1997	29.197
1998	29.047
1999	28.896
2000	28.747
2001	28.597
2002	28.448
2003	28.3
2004	25.807
2005	24.032
2006	23.427
2007	23.503
2008	24.807
2009	29.74
2010	33.063
2011	31.659
2012	31.264
2013	32.795
2014	34.376
2015	35.133
2016	35.349
2017	35.482
2018	35.615
2019	35.748
2020	35.882
2021	36.015
2022	36.148
2023	36.281
2024	36.415
2025	36.548
2026	36.681
2027	36.814
2028	36.948
2029	37.081
2030	37.214