Passage: The current clad (metallurgy) version is two layers of cupronickel, 75% copper and 25% nickel, on a core of pure copper. The total composition of the coin is 8.33% nickel, with the remainder copper. It weighs 0.2000 avoirdupois oz, 1/80th of a pound, 0.1823 troy oz, (5.670 grams). The diameter is 0.955 inches (24.26 mm), and the width of 0.069 inches (1.75 mm). The coin has a 0.069-inch (1.75-mm) reeding (or milled) edge. Owing to the introduction of the clad quarter in 1965, it was occasionally called a "Johnson Sandwich" after Lyndon B. Johnson, the US President at the time. As of 2011, it cost 11.14 cents to produce each coin. The U.S. Mint began producing silver quarters again in 1992 for inclusion in the annual Silver Proof set. Early quarters (before 1828) were slightly larger in diameter and thinner than the current coin.
What metal has the highest percentage in a cupronickel, nickel or copper?