Year	Percent
1991	98.056
1992	98.081
1993	97.918
1994	97.784
1995	97.874
1996	97.405
1997	97.618
1998	97.365
1999	97.253
2000	97.067
2001	96.598
2002	96.853
2003	96.956
2004	96.858
2005	96.731
2006	96.767
2007	96.763
2008	96.848
2009	96.882
2010	96.779
2011	96.646
2012	96.501
2013	96.331
2014	96.199
2015	96.224
2016	96.241
2017	96.235
2018	96.223
2019	96.208
2020	96.191
2021	96.174
2022	96.15