Year	Percent
1991	47.695
1992	47.816
1993	45.284
1994	44.658
1995	43.74
1996	41.369
1997	40.169
1998	41.743
1999	40.856
2000	40.417
2001	40
2002	39.548
2003	39.185
2004	38.925
2005	38.625
2006	38.437
2007	38.302
2008	38.234
2009	38.732
2010	39.054
2011	41.88
2012	42.526
2013	43.1
2014	41.84
2015	41.32
2016	42.082
2017	41.928
2018	41.955
2019	41.881
2020	41.782
2021	41.637
2022	41.464