Period	Percent
1970-01-01	0.91
1975-01-01	1.39
1980-01-01	2.06
1985-01-01	2.69
1990-01-01	3.57
1995-01-01	4.17
2000-01-01	4.12
2005-01-01	4.33
2010-01-01	5.07