Period	Percent
1970-01-01	1.10
1975-01-01	2.30
1980-01-01	3.00
1985-01-01	4.50
1990-01-01	5.55
1995-01-01	6.52
2000-01-01	7.36
2005-01-01	7.93
2010-01-01	8.27