Year	Percent
1991	40.118
1992	40.375
1993	40.657
1994	40.929
1995	41.116
1996	41.31
1997	41.549
1998	41.718
1999	41.77
2000	41.716
2001	41.61
2002	41.141
2003	41
2004	40.917
2005	40.962
2006	41.097
2007	41.301
2008	40.684
2009	39.966
2010	39.086
2011	38.362
2012	37.734
2013	37.702
2014	37.641
2015	37.532
2016	37.505
2017	37.499
2018	37.461
2019	37.49
2020	37.505
2021	37.513
2022	37.506