Year	Percent
1991	36.069
1992	35.568
1993	35.129
1994	34.629
1995	34.173
1996	34.729
1997	35.449
1998	36.366
1999	37.554
2000	38.671
2001	41.199
2002	44.02
2003	46.648
2004	47.711
2005	48.217
2006	48.842
2007	48.253
2008	47.966
2009	45.583
2010	41.799
2011	36.076
2012	34.415
2013	29.025
2014	27.164
2015	30.794
2016	29.775
2017	29.599
2018	29.373
2019	29.103
2020	28.806
2021	28.456
2022	28.031