Year	Percent
1991	40.879
1992	41.764
1993	43.103
1994	44.391
1995	47.389
1996	49.662
1997	52.51
1998	52.404
1999	54.606
2000	51.769
2001	56.53
2002	58.229
2003	60.594
2004	61.66
2005	63.487
2006	65.066
2007	66.657
2008	66.922
2009	67.724
2010	69.289
2011	68.722
2012	68.65
2013	68.131
2014	67.506
2015	66.051
2016	66.068
2017	66.413
2018	66.814
2019	67.213
2020	67.603
2021	67.992
2022	68.373