Year	Percent
1991	37.084
1992	37.416
1993	37.601
1994	37.879
1995	38.312
1996	38.47
1997	38.882
1998	39.384
1999	39.732
2000	40.259
2001	40.536
2002	39.777
2003	39.812
2004	40.263
2005	42.918
2006	45.648
2007	43.975
2008	42.538
2009	41.106
2010	39.902
2011	37.795
2012	44.615
2013	38.977
2014	39.398
2015	37.564
2016	39.027
2017	39.08
2018	39.116
2019	39.146
2020	39.188
2021	39.243
2022	39.298