Year	Percent
1991	55.085
1992	54.54
1993	54.316
1994	53.992
1995	53.406
1996	52.748
1997	52.27
1998	52.065
1999	52.24
2000	52.166
2001	52.248
2002	50.441
2003	47.417
2004	43.44
2005	41.628
2006	41.877
2007	39.543
2008	39.616
2009	37.411
2010	36.797
2011	37.274
2012	36.946
2013	38.932
2014	39.172
2015	39.366
2016	40.209
2017	39.054
2018	38.323
2019	37.672
2020	37.404
2021	37.377
2022	37.61