Period	Percent
1970-01-01	6.37
1975-01-01	7.81
1980-01-01	9.42
1985-01-01	10.45
1990-01-01	11.30
1995-01-01	11.55
2000-01-01	11.98
2005-01-01	13.15
2010-01-01	16.97