Year	Percent
1991	69.979
1992	70.114
1993	70.02
1994	70.04
1995	69.964
1996	68.457
1997	68.453
1998	68.438
1999	68.412
2000	68.372
2001	68.339
2002	68.303
2003	68.283
2004	68.308
2005	68.377
2006	68.486
2007	68.641
2008	68.836
2009	69.083
2010	69.389
2011	69.722
2012	70.101
2013	70.499
2014	70.877
2015	71.208
2016	71.776
2017	72.229
2018	72.596
2019	72.845
2020	72.969
2021	72.963
2022	72.855