Year	Percent
1991	65.61
1992	67.759
1993	68.125
1994	69.003
1995	69.527
1996	70.73
1997	71.904
1998	72.403
1999	72.53
2000	72.672
2001	72.554
2002	72.779
2003	72.167
2004	72.053
2005	71.436
2006	71.108
2007	70.807
2008	69.838
2009	70.213
2010	70.287
2011	70.216
2012	70.271
2013	70.145
2014	70.464
2015	70.786
2016	70.469
2017	70.406
2018	70.317
2019	70.215
2020	70.134
2021	70.069
2022	70.011