Questions not adding up correctly for some reason.

For some reason it never displays gold, anyone know why?

let correctAnswer = 0;

let questionOne = prompt("is Earth the 3rd planet from the sun?"); if(questionOne.toUpperCase() === "YES"){ correctAnswer += 1; }

let questionTwo = prompt("Have humans landed on the moon?"); if(questionTwo.toUpperCase() === "YES"){ correctAnswer += 1; }

let questionThree = prompt("Which planet is closest to the sun?"); if(questionThree.toUpperCase() === "MERCURY"){ correctAnswer += 1; }

let questionFour = prompt("Which planet is the biggest in our solar system?"); if(questionFour.toLowerCase() === "JUPITER"){ correctAnswer += 1; }

let questionFive = prompt("which planet is the smallest in our solar system?"); if(questionFive.toUpperCase() === "PLUTO"){ correctAnswer += 1; }

if (correctAnswer === 5){ alert("You were awarded a Gold Medal!"); } else if(correctAnswer === 3 || correctAnswer === 4 ){ alert("You were awarded a Silver Medal!"); } else if(correctAnswer === 2 || correctAnswer === 1 ){ alert("You were awarded a bronze Medal!"); } else { console.log("Sorry you got zero correct"); }