Period	Percent
1970-01-01	0.44
1975-01-01	1.00
1980-01-01	1.73
1985-01-01	3.03
1990-01-01	2.82
1995-01-01	3.43
2000-01-01	4.43
2005-01-01	10.72
2010-01-01	17.85