Year	% of total
1990	89.03897867383307
1991	88.93829887890271
1992	89.94828421654276
1993	90.250996371835
1994	90.83985640967836
1995	90.80840475497484
1996	90.42765274025477
1997	90.71594913789507
1998	90.14210065209971
1999	90.06338815150798
2000	89.83793466109275
2001	90.50276795353977
2002	90.19362885599686
2003	90.5455995525391
2004	89.95226488178723
2005	90.06279273873847
2006	89.58711941505756
2007	91.7479619593104
2008	91.3081952919198