Year	Percent
1991	60.785
1992	60.704
1993	60.636
1994	60.58
1995	60.542
1996	60.508
1997	60.497
1998	60.501
1999	60.514
2000	60.53
2001	60.525
2002	60.542
2003	60.543
2004	60.566
2005	60.602
2006	60.596
2007	60.6
2008	60.626
2009	60.622
2010	60.653
2011	60.68
2012	60.718
2013	60.747
2014	60.766
2015	60.78
2016	60.813
2017	60.843
2018	60.872
2019	60.902
2020	60.936
2021	60.964
2022	60.998