Year	% of total
1989	99.3
1990	99.1
1991	99.5
1992	99.8
1993	99
1994	99
1995	98.9
1996	99.9
1997	99.9
1998	99.88003
1999	99
2000	99.8
2001	98.9
2002	99.2
2003	99.2
2004	99.4
2005	99.4
2006	99.4
2007	99.6
2008	99.6
2009	99.6
2010	99.5
2013	99.7
2014	99.7
2015	93.4
2016	95.1
2017	93.9
2018	93
2019	92.3
2020	94.6
2021	94.5