Year	Percent
1990	69.98
1991	71.31
1992	73.29
1993	74.13
1994	73.95
1995	73.92
1996	73.99
1997	74.46
1998	75.58
1999	75.32
2000	76.18
2001	77.89
2003	80.85
2004	81.32