Period	Percent
1970-01-01	3.40
1975-01-01	4.67
1980-01-01	4.76
1985-01-01	5.46
1990-01-01	6.90
1995-01-01	7.29
2000-01-01	9.15
2005-01-01	9.37
2010-01-01	11.85