Period	Percent
1970-01-01	1.60
1975-01-01	2.32
1980-01-01	3.50
1985-01-01	5.49
1990-01-01	7.66
1995-01-01	8.77
2000-01-01	11.23
2005-01-01	11.15
2010-01-01	12.72