Period	Percent
1970-01-01	2.00
1975-01-01	4.30
1980-01-01	5.00
1985-01-01	5.45
1990-01-01	5.84
1995-01-01	6.49
2000-01-01	7.27
2005-01-01	8.09
2010-01-01	11.30