Period	Percent
1970-01-01	0.10
1975-01-01	0.70
1980-01-01	1.30
1985-01-01	1.66
1990-01-01	1.79
1995-01-01	1.91
2000-01-01	2.01
2005-01-01	2.29
2010-01-01	2.63