Year	Percent
1991	46.866
1992	47.434
1993	46.766
1994	46.779
1995	46.181
1996	45.782
1997	45.295
1998	43.605
1999	42.201
2000	42.01
2001	39.674
2002	38.989
2003	38.655
2004	36.3
2005	36.055
2006	36.09
2007	35.388
2008	35.058
2009	35.323
2010	35.66
2011	36.276
2012	36.723
2013	37.065
2014	36.058
2015	35.042
2016	34.165
2017	33.871
2018	33.541
2019	33.045
2020	32.672
2021	32.252
2022	31.777