Year	Percent
1991	70.61
1992	69.916
1993	69.626
1994	69.807
1995	69.1
1996	68.731
1997	69.184
1998	68.535
1999	68.652
2000	69.714
2001	69.319
2002	70.259
2003	71.544
2004	70.985
2005	69.497
2006	68.993
2007	68.859
2008	68.288
2009	68.371
2010	67.678
2011	68.396
2012	68.049
2013	67.967
2014	67.949
2015	67.604
2016	67.318
2017	68.329
2018	68.366
2019	68.007
2020	67.851
2021	67.696
2022	67.532