Year	Percent
1990	36.205
1991	36.199
1992	34.564
1993	28.435
1994	33.053
1995	32.628
1996	32.209
1997	30.333
1998	30.636
1999	31.284
2000	27.872
2001	28.387
2002	29.291
2003	27.947
2004	25.16
2005	25.18
2006	25.015
2007	25.116
2008	26.123
2009	27.808
2010	29.592
2011	30.994
2012	31.677
2013	33.126
2014	33.448
2015	34.861
2016	36.152
2017	36.126
2018	36.104
2019	36.079
2020	36.046
2021	36.02
2022	35.993
2023	35.961
2024	35.921
2025	35.873
2026	35.818
2027	35.752
2028	35.681
2029	35.608
2030	35.536