Year	% of total
1990	87.88503019074419
1991	87.74786696639333
1992	87.55991823118161
1993	87.39610421415257
1994	86.79157052487356
1995	87.07170975391652
1996	87.11109973723113
1997	87.32487640268188
1998	88.02312469099691
1999	88.48584462315567
2000	88.9034144810693
2001	88.68746666390577
2002	89.16908605530661
2003	89.09316765933718
2004	89.10303985594106
2005	89.22418320696907
2006	88.63300797980624
2007	88.65978525753633
2008	88.44643250968447