Period	Percent
1970-01-01	0.27
1975-01-01	0.50
1980-01-01	0.67
1985-01-01	1.01
1990-01-01	1.30
1995-01-01	1.49
2000-01-01	1.78
2005-01-01	2.23
2010-01-01	2.25