Period	Percent
1970-01-01	0.78
1975-01-01	1.00
1980-01-01	1.92
1985-01-01	3.30
1990-01-01	3.73
1995-01-01	4.12
2000-01-01	4.66
2005-01-01	5.18
2010-01-01	5.12