Period	Percent
1970-01-01	1.89
1975-01-01	2.50
1980-01-01	3.75
1985-01-01	4.93
1990-01-01	6.36
1995-01-01	7.50
2000-01-01	9.27
2005-01-01	10.60
2010-01-01	6.78