Year	Percent
1991	55.048
1992	54.246
1993	53.263
1994	51.943
1995	50.911
1996	50.243
1997	49.12
1998	48.152
1999	47.658
2000	46.858
2001	46.052
2002	45.392
2003	45.163
2004	44.645
2005	43.844
2006	42.947
2007	41.884
2008	41.665
2009	41.968
2010	41.45
2011	41.018
2012	40.897
2013	40.769
2014	40.709
2015	40.514
2016	40.014
2017	39.927
2018	39.85
2019	39.77
2020	39.691
2021	39.613
2022	39.535