Year	% of total
1990	99.94940039467693
1991	99.95353039886407
1992	99.95478122090704
1993	99.94306092481045
1994	99.93948466413988
1995	99.91973673649571
1996	99.93256911665543
1997	99.91940745289173
1998	99.880810488677
1999	99.92834515009805
2000	99.89655568752156
2001	99.88030163986753
2002	99.87526459026309
2003	99.8798212340857
2004	99.87824415251522
2005	99.86757533671393
2006	99.86797019898778
2007	99.81777624179207
2008	99.76318192193563
2009	99.58519884119042
2010	99.52142140707838
2011	99.48136645962732
2012	99.27595051787395
2013	98.98117878566669
2014	99.09601266733841
2015	98.92905345930403