Period	Percent
1970-01-01	0.59
1975-01-01	0.70
1980-01-01	0.78
1985-01-01	0.80
1990-01-01	0.70
1995-01-01	0.85
2000-01-01	1.17
2005-01-01	1.83
2010-01-01	2.76