Year	% of total
1990	80.67418692418693
1991	81.01513442842702
1992	80.70253902232784
1993	81.54883407429328
1994	80.57390514137919
1995	82.00858241943328
1996	81.37880713260913
1997	81.32683798156943
1998	80.65660315317655
1999	79.63709569660679
2000	79.98685775758118
2001	79.63665503771023
2002	79.90016346599832
2003	81.2151067323481
2004	80.89148675006726
2005	78.58780878758681
2006	77.84729863070878
2007	77.1768851303735
2008	78.73743179064596