Year	Percent
1991	36.779
1992	34.911
1993	33.707
1994	32.7
1995	27.979
1996	31.82
1997	34.861
1998	32.801
1999	30.496
2000	28.418
2001	30.382
2002	29.407
2003	29.221
2004	34.741
2005	37.872
2006	40.236
2007	37.727
2008	38.396
2009	38.798
2010	37.874
2011	35.975
2012	33.08
2013	35.592
2014	33.237
2015	31.322
2016	33.653
2017	33.189
2018	32.617
2019	31.996
2020	31.344
2021	30.572
2022	29.699