Year	% of total
1990	99.4
1991	99.3
1992	99
1993	98.3
1994	98.2
1995	98
1996	98
1997	98.4
1998	99
1999	99.8
2000	99.7
2001	99.6
2002	99.7
2003	99.7
2004	99.5
2005	99.9
2006	99.9
2007	98.6
2008	99.6
2009	99.7
2010	99.8
2011	99.5
2012	99.9
2013	98.2
2014	99.9
2015	99.9
2016	100
2017	100
2018	100
2019	100
2020	100