Year	Percent
1991	52.216
1992	50.661
1993	50.453
1994	49.991
1995	49.63
1996	50.609
1997	51.182
1998	49.709
1999	51.674
2000	52.418
2001	50.756
2002	44.793
2003	44.481
2004	44.624
2005	44.646
2006	44.417
2007	46.259
2008	38.243
2009	38.136
2010	36.794
2011	37.74
2012	38.933
2013	39.972
2014	39.198
2015	39.251
2016	39.2
2017	39.319
2018	39.354
2019	39.39
2020	39.377
2021	39.378
2022	39.377