Year	Percent
1991	35.533
1992	35.871
1993	35.347
1994	35.083
1995	40.318
1996	40.566
1997	40.084
1998	41.054
1999	44.151
2000	36.89
2001	30.875
2002	27.989
2003	27.729
2004	24.713
2005	25.227
2006	24.548
2007	23.989
2008	22.998
2009	23.496
2010	21.797
2011	18.074
2012	17.826
2013	17.286
2014	17.74
2015	17.895
2016	17.356
2017	17.556
2018	17.517
2019	17.475
2020	17.434
2021	17.394
2022	17.355