Year	Percent
1991	74.658
1992	73.05
1993	71.955
1994	70.958
1995	70.188
1996	69.577
1997	64.585
1998	63.968
1999	64.528
2000	64.277
2001	63.065
2002	61.001
2003	57.746
2004	55.921
2005	52.66
2006	49.675
2007	48.659
2008	48.616
2009	47.582
2010	46.74
2011	46.483
2012	45.941
2013	44.97
2014	44.662
2015	42.383
2016	40.36
2017	39.469
2018	38.26
2019	37.108
2020	36.004
2021	34.945
2022	34.061