Where is the mint mark on a 1964 US nickel?

The mint mark positions for Jefferson nickels are:

• 1938-late 1942 and 1946 to 1964: to the right of Monticello on the back
• Late 1942 to 1945: above the dome of Monticello
• 1965 to 1967: No mint marks were used on any US Coins regardless of where they were made
• 1968 to 2004: to the right of the tail of Jefferson's wig
• 2005: Below the Word Liberty
• 2006-present: Below the date

Possible mint marks are:

• "P" or no mint mark = Philadelphia
• "D" = Denver
• "S" = San Francisco