Period	Percent
1970-01-01	0.29
1975-01-01	0.20
1980-01-01	0.83
1985-01-01	2.00
1990-01-01	4.22
1995-01-01	4.40
2000-01-01	4.64
2005-01-01	5.62
2010-01-01	7.48