Year	Percent
1991	42.665
1992	42.411
1993	41.955
1994	41.249
1995	41.518
1996	41.163
1997	41.898
1998	42.466
1999	41.57
2000	41.888
2001	42.307
2002	41.91
2003	40.783
2004	40.026
2005	40.706
2006	41.039
2007	41.597
2008	41.882
2009	42.317
2010	42.318
2011	42.009
2012	41.729
2013	40.903
2014	40.889
2015	40.075
2016	39.761
2017	39.806
2018	39.748
2019	39.687
2020	39.615
2021	39.546
2022	39.489