Period	Percent
1970-01-01	5.63
1975-01-01	10.14
1980-01-01	11.76
1985-01-01	12.77
1990-01-01	13.19
1995-01-01	11.99
2000-01-01	12.23
2005-01-01	15.45
2010-01-01	23.74