Year	Percent
1991	64.547
1992	60.865
1993	60.1
1994	58.021
1995	56.844
1996	52.082
1997	48.431
1998	47.382
1999	45.546
2000	43.999
2001	41.791
2002	42.011
2003	41.715
2004	39.875
2005	40.384
2006	40.249
2007	39.279
2008	38.585
2009	39.44
2010	40.342
2011	38.943
2012	38.56
2013	39.399
2014	39.066
2015	40.045
2016	40.411
2017	40.1
2018	40.112
2019	40.11
2020	40.101
2021	40.092
2022	40.076