Period	Percent
1970-01-01	0.11
1975-01-01	0.18
1980-01-01	0.27
1985-01-01	0.31
1990-01-01	0.33
1995-01-01	0.41
2000-01-01	0.50
2005-01-01	0.92
2010-01-01	2.04