Year	Percent
1991	71.377
1992	68.361
1993	66.547
1994	65.231
1995	64.147
1996	64.11
1997	64.663
1998	67.397
1999	66.772
2000	67.451
2001	68.05
2002	67.963
2003	66.259
2004	65.639
2005	64.641
2006	64.853
2007	64.592
2008	64.388
2009	61.521
2010	60.352
2011	58.569
2012	55.775
2013	54.547
2014	55.75
2015	56.366
2016	57.172
2017	58.405
2018	58.899
2019	58.889
2020	58.532
2021	58.114
2022	57.696