Year	% of total
1990	95.3
1991	94.5
1993	97.6
1994	96.2
1995	96.2
1996	96.3
1997	96.2
1998	96.7
1999	96.4
2000	96.9
2001	98.4
2002	96.9
2003	96.7
2004	97
2005	97.2
2006	99.3
2007	99
2008	98.8
2009	99.8
2010	99.7
2011	99.6
2012	99.3
2013	98.8
2014	99.7
2015	99.9
2016	99.8
2021	99.8