Only 2 questions show up

var questions = [
  ['How many states are in the United States?', 50],
  ['How many continents are there?', 7],
  ['How many planets are there?', 8]
  ['How many people have served as president of UNited States?', 6]
];
var correctAnswers = 0;
var question;
var answer;
var response;
var html;
var correct = [];
var wrong = [];

function print(message) {
  document.write(message);
}

function buildList( array ) {
var listHTML = 'ol';
for (var i = 0; i < array.length; i += 1) {
  listHTML += '<li>' + array[i] + '</li>';
}
  listHTML += '</ol>';
  return listHTML;
  }
for (var i = 0; i < questions.length; i += 1) {
  question = questions[i][0];
  answer = questions[i][1];
  response = prompt(question);
  response = parseInt(response);
  if (response === answer) {
    correctAnswers += 1;
    correct.push(question);
  } else {
    wrong.push(question);
  }
}

html = "You got " + correctAnswers + " question(s) right.";
html += "<h2>You got these answers correct:</h2>";
html += buildList(correct);
html += "<h2>You got these answers incorrect:</h2>";
html += buildList(wrong);
print(html);