Year	% of total
1989	97.3
1990	97.3
1991	97.2
1992	96.5
1993	96.3
1994	99.6
1995	91.5
1996	87.9
1997	90.4
1998	91.5
1999	92.4
2000	80.7
2001	88
2002	94
2003	95.8
2004	95.9
2005	94.4
2006	88.6
2007	93
2008	98
2009	99.8
2010	99.4
2011	97.2
2012	99.8
2013	99.9
2014	99.9
2015	99.8
2016	99.8
2017	99.8
2018	99.4
2019	99.9
2020	99.9
2021	99.9