Year	% of total
1989	94.6
1990	96.6
1991	91.3
1992	91.1
1993	90.8
1998	96
1999	96.4
2000	95.5
2001	96.6
2002	97.4
2003	97.2
2004	97.5
2005	98.3
2006	98.8
2007	99.4
2008	99.6
2009	99.7
2010	99.6
2011	99.8
2012	99.8
2013	99.9
2014	99.9
2015	99.9
2016	99.9
2017	99.9
2018	99.8
2019	99.8
2020	99.8
2021	99.8