Year	Percent
1980-01-01	3.930
1981-01-01	4.980
1982-01-01	5.270
1983-01-01	5.160
1984-01-01	5.250
1985-01-01	4.890
1986-01-01	3.570
1987-01-01	3.900
1988-01-01	3.790
1989-01-01	5.650
1990-01-01	6.760
1991-01-01	8.090
1992-01-01	7.400
1993-01-01	6.300
1994-01-01	5.730
1995-01-01	4.950
1996-01-01	4.910
1997-01-01	4.510
1998-01-01	4.030
1999-01-01	3.880
2000-01-01	3.680
2001-01-01	3.450
2002-01-01	3.380
2003-01-01	3.280
2004-01-01	3.000
2005-01-01	2.525