Year	Percent
1991	45.33
1992	45.904
1993	44.908
1994	45.197
1995	43.784
1996	43.706
1997	42.39
1998	41.309
1999	39.31
2000	38.968
2001	35.775
2002	35.319
2003	35.149
2004	31.683
2005	31.783
2006	31.634
2007	30.677
2008	30.716
2009	30.563
2010	31.053
2011	31.438
2012	31.421
2013	31.926
2014	30.445
2015	29.632
2016	29.491
2017	29.272
2018	28.934
2019	28.309
2020	27.87
2021	27.378
2022	26.804