Year	Percent
1991	70.317
1992	64.466
1993	66.238
1994	66.436
1995	67.341
1996	66.829
1997	67.021
1998	67.467
1999	67.092
2000	67.63
2001	68.009
2002	67.851
2003	68.676
2004	68.799
2005	69.266
2006	68.214
2007	66.574
2008	63.398
2009	62.869
2010	61.829
2011	61.727
2012	61.557
2013	60.683
2014	60.493
2015	60.151
2016	59.751
2017	59.924
2018	60.033
2019	60.518
2020	60.786
2021	61.095
2022	61.339