Year	Percent
1991	49.679
1992	48.292
1993	46.963
1994	45.488
1995	44.061
1996	42.777
1997	42.046
1998	41.56
1999	41.066
2000	40.862
2001	40.325
2002	41.904
2003	43.348
2004	44.849
2005	43.29
2006	41.859
2007	40.518
2008	38.176
2009	37.21
2010	35.208
2011	35.435
2012	33.981
2013	34.532
2014	32.535
2015	32.136
2016	32.414
2017	31.557
2018	30.811
2019	30.052
2020	29.292
2021	28.578
2022	27.919