Period	Percent
1970-01-01	8.16
1975-01-01	9.91
1980-01-01	12.04
1985-01-01	13.43
1990-01-01	14.45
1995-01-01	14.45
2000-01-01	14.90
2005-01-01	14.53
2010-01-01	17.89