Year	Percent
1991	43.632
1992	43.341
1993	41.479
1994	41.356
1995	40.15
1996	40.24
1997	40.276
1998	40.934
1999	40.89
2000	40.841
2001	40.355
2002	38.613
2003	38.908
2004	38.819
2005	37.854
2006	38.653
2007	36.757
2008	39.906
2009	40.213
2010	40.351
2011	40.288
2012	40.912
2013	41.021
2014	41.075
2015	41.182
2016	40.998
2017	40.983
2018	40.92
2019	40.833
2020	40.746
2021	40.665
2022	40.593