Year	Percent
1991	36.83
1992	37.675
1993	37.766
1994	37.628
1995	37.198
1996	37.488
1997	39.406
1998	39.171
1999	41.059
2000	40.889
2001	37.941
2002	38.858
2003	38.447
2004	38.128
2005	41.804
2006	50.46
2007	49.72
2008	50.974
2009	52.071
2010	50.65
2011	52.523
2012	52.79
2013	54.891
2014	56.603
2015	58.364
2016	58.774
2017	59.73
2018	61.336
2019	62.129
2020	62.962
2021	63.786
2022	64.431