Year	Percent
1991	37.286
1992	36.035
1993	35.29
1994	35.843
1995	37.161
1996	38.486
1997	38.769
1998	38.159
1999	37.467
2000	36.7
2001	33.532
2002	35.034
2003	34.687
2004	34.467
2005	33.701
2006	33.265
2007	32.946
2008	32.941
2009	31.477
2010	30.847
2011	31.029
2012	30.435
2013	29.492
2014	28.99
2015	28.692
2016	28.522
2017	28.456
2018	28.256
2019	28.127
2020	28.052
2021	27.965
2022	27.874