Period	Percent
1970-01-01	0.87
1975-01-01	1.37
1980-01-01	3.18
1985-01-01	4.85
1990-01-01	6.93
1995-01-01	8.76
2000-01-01	10.54
2005-01-01	11.66
2010-01-01	12.18