| JAN | FEB | MAR | APR | MAY | JUN | JUL | AUG | SEP | OCT | NOV | DEC | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2022 | 1.60 | 1.60 | ||||||||||
| 2021 | 0.60 | 0.60 | 0.80 | 1.00 | 1.20 | 1.20 | 1.20 | 1.20 | 1.00 | 1.00 | 1.40 | 1.60 |
| 2020 | 2.00 | 2.20 | 1.80 | 1.20 | 0.80 | 0.60 | 0.60 | 0.40 | 0.40 | 0.40 | 0.40 | 0.60 |
| 2019 | 3.40 | 3.20 | 3.20 | 3.00 | 2.80 | 2.80 | 2.60 | 2.20 | 2.20 | 1.80 | 2.00 | 2.00 |
| 2018 | 2.60 | 2.80 | 3.00 | 3.20 | 3.20 | 3.40 | 3.40 | 3.40 | 3.40 | 3.40 | 3.60 | 3.60 |
| 2017 | 2.40 | 2.60 | 2.40 | 2.60 | 2.40 | 2.40 | 2.20 | 2.40 | 2.40 | 2.20 | 2.40 | 2.60 |
| 2016 | 2.20 | 2.20 | 1.80 | 1.80 | 1.80 | 1.80 | 1.80 | 1.40 | 1.40 | 1.60 | 1.60 | 1.80 |
| 2015 | 2.20 | 2.00 | 1.80 | 2.00 | 1.80 | 2.00 | 2.20 | 2.20 | 2.20 | 2.00 | 2.00 | 2.00 |
| 2014 | 2.20 | 2.40 | 2.20 | 2.20 | 2.40 | 2.20 | 2.20 | 2.20 | 2.20 | 2.20 | 2.20 | 2.00 |
| 2013 | 1.00 | 1.20 | 1.40 | 1.40 | 1.20 | 1.20 | 1.40 | 2.00 | 2.00 | 2.40 | 2.00 | 2.00 |
| 2012 | 1.40 | 1.40 | 1.40 | 1.40 | 1.60 | 1.20 | 1.20 | 1.00 | 1.00 | 1.20 | 1.00 | 1.20 |
| 2011 | 2.40 | 2.80 | 3.00 | 3.00 | 3.00 | 2.80 | 2.40 | 2.20 | 2.00 | 1.40 | 1.40 | 1.60 |
| 2010 | 3.00 | 3.40 | 3.20 | 3.20 | 3.40 | 3.20 | 2.80 | 2.60 | 2.40 | 2.00 | 2.00 | 1.80 |
| 2009 | 2.40 | 2.00 | 2.40 | 2.60 | 2.40 | 2.80 | 3.40 | 3.40 | 3.40 | 3.20 | 3.20 | 3.20 |
| 2008 | 4.40 | 4.20 | 3.60 | 3.40 | 3.20 | 3.80 | 4.20 | 4.20 | 4.20 | 3.80 | 3.60 | 3.40 |
| 2007 | 5.60 | 5.60 | 5.80 | 5.60 | 5.60 | 5.60 | 6.00 | 6.20 | 5.80 | 5.20 | 5.20 | 5.00 |
| 2006 | 5.40 | 5.20 | 5.40 | 5.60 | 5.80 | 6.00 | 6.00 | 6.20 | 6.00 | 5.80 | 5.60 | 5.80 |
| 2005 | 4.60 | 4.60 | 4.60 | 5.00 | 5.20 | 4.80 | 4.60 | 4.80 | 5.00 | 5.00 | 5.00 | 5.40 |
| 2004 | 4.20 | 4.20 | 4.00 | 3.80 | 3.80 | 4.60 | 5.00 | 4.80 | 4.60 | 4.40 | 4.20 | 4.20 |
| 2003 | 4.20 | 4.00 | 3.80 | 3.60 | 3.80 | 3.60 | 3.00 | 3.20 | 4.20 | 4.40 | 4.00 | 4.20 |
| 2002 | 5.40 | 5.60 | 5.40 | 5.60 | 6.00 | 5.80 | 5.60 | 5.20 | 4.60 | 4.20 | 3.60 | 4.00 |
| 2001 | 6.80 | 6.20 | 6.20 | 6.00 | 5.80 | 6.00 | 6.20 | 6.00 | 5.80 | 5.60 | 5.00 | 4.80 |
| 2000 | 7.40 | 8.00 | 8.20 | 8.00 | 7.80 | 8.00 | 8.00 | 7.60 | 7.60 | 7.40 | 7.20 | 7.00 |
| 1999 | 5.60 | 5.60 | 5.80 | 6.40 | 6.20 | 6.40 | 7.00 | 7.20 | 7.20 | 7.20 | 7.40 | 7.40 |
| 1998 | 7.20 | 6.80 | 6.80 | 6.80 | 6.80 | 7.00 | 6.80 | 6.80 | 6.60 | 6.20 | 5.40 | 5.40 |
| 1997 | 7.40 | 7.60 | 7.80 | 7.80 | 8.20 | 8.20 | 8.00 | 7.60 | 7.60 | 7.60 | 7.40 | 7.20 |
| 1996 | 6.80 | 6.80 | 6.60 | 7.00 | 7.60 | 8.00 | 8.20 | 8.20 | 8.00 | 8.00 | 8.00 | 7.60 |
| 1995 | 9.60 | 9.60 | 9.40 | 8.80 | 8.60 | 8.20 | 7.60 | 7.20 | 7.60 | 7.60 | 7.40 | 7.20 |
| 1994 | 6.40 | 6.40 | 6.40 | 7.00 | 7.80 | 8.40 | 8.20 | 8.40 | 8.40 | 8.60 | 9.00 | 9.40 |
| 1993 | 7.60 | 7.60 | 7.00 | 6.60 | 6.60 | 6.40 | 6.60 | 6.40 | 6.40 | 6.00 | 6.00 | 6.20 |
| 1992 | 8.20 | 7.60 | 8.00 | 8.40 | 8.60 | 8.40 | 8.20 | 7.80 | 7.20 | 7.00 | 6.80 | 7.40 |
| 1991 | 9.80 | 9.60 | 9.40 | 9.60 | 9.60 | 9.60 | 9.60 | 9.80 | 9.60 | 9.00 | 8.60 | 8.60 |
| 1990 | 9.60 | 9.80 | 10.20 | 10.60 | 10.60 | 11.00 | 10.60 | 10.40 | 10.20 | 10.60 | 10.60 | 10.20 |
| 1989 | 10.00 | 10.00 | 10.00 | 10.00 | 11.60 | 11.20 | 10.60 | 10.00 | 9.60 | 10.20 | 10.00 | 9.80 |
§7520 went in effect May 1, 1989. Dates before this were required to use 10%.