A 1964 Jefferson U.S. nickel has 0 percent silver content. The only widely circulated U.S. coins of the time with significant silver content were quarters and dimes.
According to the United States Mint, when the 5-cent piece was first introduced, it was called a half-dime and had a high silver content. Rising metals prices caused a change to a nickel-copper combination in 1866. Coinflation.com points out that during World War II, from 1942 to 1945, nickels had about a 35 percent silver content due to nickel being valued for armor plating. Quarters had a 90 percent silver content until the Coinage Act of 1965.