Year	Percent
1991	83.6
1992	84.179
1993	84.01
1994	84.346
1995	84.797
1996	85.094
1997	85.235
1998	85.858
1999	86.133
2000	86.338
2001	87.045
2002	87.437
2003	87.842
2004	87.957
2005	88.236
2006	88.138
2007	88.39
2008	88.471
2009	88.886
2010	89.103
2011	89.578
2012	89.718
2013	90.024
2014	90.043
2015	90.471
2016	90.396
2017	90.649
2018	90.814
2019	90.966
2020	91.09
2021	91.248
2022	91.374