Year	Percent
1991	67.154
1992	65.547
1993	62.92
1994	60.719
1995	58.612
1996	56.961
1997	55.973
1998	55.38
1999	54.703
2000	53.826
2001	52.997
2002	51.942
2003	50.359
2004	48.554
2005	47.001
2006	45.407
2007	43.796
2008	42.388
2009	41.548
2010	40.259
2011	39.166
2012	38.468
2013	37.873
2014	37.298
2015	36.977
2016	36.535
2017	36.511
2018	36.44
2019	36.374
2020	36.31
2021	36.248
2022	36.188