Period	Percent
1970-01-01	9.45
1975-01-01	10.20
1980-01-01	11.00
1985-01-01	12.71
1990-01-01	15.11
1995-01-01	17.42
2000-01-01	19.11
2005-01-01	22.19
2010-01-01	33.20