Year	Percent
1991	53.839
1992	52.684
1993	49.903
1994	49.03
1995	47.134
1996	46.98
1997	45.926
1998	44.001
1999	41.828
2000	42.246
2001	41.333
2002	40.579
2003	40.218
2004	41.161
2005	40.872
2006	40.41
2007	41.501
2008	39.87
2009	36.059
2010	32.635
2011	34.066
2012	35.387
2013	36.782
2014	37.06
2015	37.455
2016	38.275
2017	38.561
2018	38.726
2019	38.369
2020	37.708
2021	36.643
2022	35.271