Year	% of total
1989	96.6
1990	97
1991	97.4
1996	98.9
1997	98.7
1998	99.3
1999	99.6
2000	98.9
2001	99.9
2002	99.9
2003	99.9
2004	99.9
2005	99.9
2006	99.4
2007	99.9
2008	99.9
2009	99.9
2010	99.9
2011	99.9
2012	99.9
2014	99.9
2015	99.9
2016	99.9
2017	99.9
2018	99.9
2019	99.9