Period	Percent
1970-01-01	1.10
1975-01-01	1.76
1980-01-01	2.90
1985-01-01	3.63
1990-01-01	4.86
1995-01-01	5.08
2000-01-01	5.30
2005-01-01	12.87
2010-01-01	12.53