Period	Percent
1970-01-01	0.00
1975-01-01	0.74
1980-01-01	1.56
1985-01-01	2.89
1990-01-01	4.47
1995-01-01	6.12
2000-01-01	7.62
2005-01-01	8.40
2010-01-01	9.36