Year	Percent
1991	40.584
1992	39.75
1993	39.988
1994	39.272
1995	40.246
1996	39.216
1997	40.669
1998	44.374
1999	42.548
2000	43.761
2001	41.395
2002	42.13
2003	42.112
2004	40.571
2005	40.727
2006	44.391
2007	43.509
2008	43.936
2009	42.355
2010	44.492
2011	45.081
2012	43.588
2013	44.252
2014	43.533
2015	43.186
2016	42.9
2017	42.845
2018	42.785
2019	42.721
2020	42.655
2021	42.586
2022	42.516