Year	% of total
1990	88.27322280240332
1991	87.36179589388688
1992	87.33603939805332
1993	87.45601600231417
1994	52.91987234904342
1995	53.46543643633342
1996	53.3266143730947
1997	54.62113288569194
1998	55.26503219354339
1999	55.75882485808157
2000	55.76933122616961
2001	55.749091970063496
2002	56.061390260830244
2003	56.99698426792264
2004	57.20190010563989
2005	58.46250979150297
2006	58.504103738635784
2007	59.60448062847781
2008	60.12021426874788