Year	Percent
1991	39.263
1992	42.26
1993	40.672
1994	44.722
1995	45.735
1996	49.741
1997	48.947
1998	51.477
1999	51.49
2000	50.709
2001	48.138
2002	47.351
2003	44.774
2004	48.796
2005	48.601
2006	47.022
2007	47.345
2008	45.049
2009	40.723
2010	38.785
2011	40.607
2012	35.543
2013	36.46
2014	32.923
2015	32.237
2016	34.625
2017	34.517
2018	34.514
2019	34.417
2020	34.374
2021	34.469
2022	34.598