Year	Percent
1991	68.263
1992	68.301
1993	67.31
1994	68.264
1995	67.025
1996	67.779
1997	67.717
1998	67.712
1999	69.598
2000	68.69
2001	67.487
2002	67.171
2003	67.166
2004	67.878
2005	67.808
2006	68.528
2007	69.368
2008	70.351
2009	71.268
2010	69.964
2011	69.206
2012	69.027
2013	68.608
2014	67.822
2015	66.912
2016	67.221
2017	67.594
2018	67.856
2019	68.079
2020	68.282
2021	68.465
2022	68.618