Year	% of total
1990	86.75008515566495
1991	86.34331712788304
1992	85.95871922057756
1993	85.60421702640794
1994	70.78450466197441
1995	71.03765510293438
1996	71.2913554889402
1997	71.5719607656512
1998	72.95788016050129
1999	73.16872204357438
2000	73.73969595349355
2001	73.30274935144745
2002	74.30223626624655
2003	74.64720585954383
2004	74.63632905625954
2005	75.41985140036647
2006	74.73119417196939
2007	75.3742443484566
2008	75.55644049215289