Year	% of total
1989	100
1990	100
1991	100
1992	100
1993	100
1994	100
1995	100
1996	100
1997	100
1998	100
1999	100
2000	100
2001	99.4
2002	99.4
2003	99.5
2004	99.5
2005	99.5
2006	99.5
2007	99.2
2008	99.5
2009	99.5
2010	99.2
2011	99
2012	99.5
2013	98.6
2014	98.3
2015	97
2016	98.1
2017	98.8
2018	98
2019	98.3
2020	98.2
2021	98