| Date | First Ounce | Additional Ounce |
| Mar 3, 1863 | 6 cents | 6 cents |
| Mar 3, 1883 | 4 cents | 4 cents |
| Jul 1, 1885 | 2 cents | 2 cents |
| Nov 3, 1917 | 3 cents | 3 cents |
| Jul 1, 1919 | 2 cents | 2 cents |
| Jul 6, 1932 | 3 cents | 3 cents |
| Aug 1, 1958 | 4 cents | 4 cents |
| Jan 1, 1963 | 5 cents | 5 cents |
| Jan 7, 1968 | 6 cents | 6 cents |
| May 16, 1971 | 8 cents | 8 cents |
| Mar 2, 1974 | 10 cents | 10 cents |
| Sep 14, 1975 | 10 cents | 9 cents |
| Dec 31, 1975 | 13 cents | 11 cents |
|
| Dec 31, 1975 | 13 cents | 11 cents |
| May 29, 1978 | 15 cents | 13 cents |
| Mar 22, 1981 | 18 cents | 17 cents |
| Nov 1, 1981 | 20 cents | 17 cents |
| Feb 17, 1985 | 22 cents | 17 cents |
| Apr 3, 1988 | 25 cents | 20 cents |
| Feb 3, 1991 | 29 cents | 23 cents |
| Jan 1, 1995 | 32 cents | 23 cents |
| Jan 10, 1999 | 33 cents | 22 cents |
| Jan 7, 2001 | 34 cents | 21 cents |
| Jul 1, 2001 | 34 cents | 23 cents |
| Jun 30, 2002 | 37 cents | 23 cents |
| Jan 8, 2006 | 39 cents | 24 cents |
| May 14, 2007 | 41 cents | 17 cents |
|
