Period	Percent
1970-01-01	0.07
1975-01-01	0.17
1980-01-01	0.38
1985-01-01	0.55
1990-01-01	0.75
1995-01-01	1.03
2000-01-01	1.34
2005-01-01	1.34
2010-01-01	1.18