Year	Percent
1991	52.667
1992	53.606
1993	53.271
1994	55.729
1995	54.808
1996	51.355
1997	51.373
1998	53.058
1999	50.705
2000	47.109
2001	46.341
2002	40.044
2003	38.159
2004	42.781
2005	42.68
2006	45.451
2007	48.711
2008	51.852
2009	52.589
2010	53.022
2011	53.551
2012	52.507
2013	52.311
2014	51.185
2015	47.419
2016	45.744
2017	45.584
2018	45.555
2019	45.503
2020	45.433
2021	45.359
2022	45.298