Year	Percent
1991	45.021
1992	45.483
1993	44.378
1994	46.641
1995	44.257
1996	44.081
1997	40.983
1998	43.908
1999	43.811
2000	44.504
2001	44.543
2002	38.437
2003	38.212
2004	38.497
2005	38.156
2006	37.659
2007	37.012
2008	37.52
2009	36.932
2010	35.431
2011	35.284
2012	33.554
2013	33.466
2014	33.763
2015	32.553
2016	33.786
2017	33.486
2018	32.6
2019	31.706
2020	30.843
2021	30.01
2022	29.293