Year	Percent
1991	59.175
1992	59.839
1993	58.055
1994	57.36
1995	56.454
1996	55.492
1997	54.427
1998	48.089
1999	44.95
2000	45.48
2001	43.803
2002	43.347
2003	42.258
2004	43.131
2005	43.5
2006	38.36
2007	40.266
2008	38.726
2009	38.116
2010	38.071
2011	37.647
2012	36.986
2013	34.105
2014	33.775
2015	32.631
2016	31.535
2017	31.184
2018	30.705
2019	30.257
2020	30.564
2021	30.693
2022	30.674