Year	Percent
1991	44.056
1992	44.453
1993	44.378
1994	46.944
1995	46.222
1996	45.541
1997	45.298
1998	45.524
1999	45.642
2000	46.563
2001	46.549
2002	46.074
2003	45.266
2004	44.949
2005	43.586
2006	42.069
2007	41.292
2008	39.885
2009	37.618
2010	36.652
2011	36.969
2012	36.377
2013	36.897
2014	37.071
2015	40.053
2016	38.821
2017	38.258
2018	37.737
2019	37.202
2020	36.665
2021	36.103
2022	35.545