My code is only listing the last correct answer, not the correct answer, please help.

var questions = [
 ['What is the capital of  Peru?','lima'],
 ['What is the capital of Argentina?','buenos aires'],
 ['What is the capital of Bolivia?','la paz']
]

var correctAnswers = 0;
var question;
var answer;
var response;
var correct = [];
var incorrect = [];

function print(message) {
  var outputDiv = document.getElementById('output');
  outputDiv.innerHTML = message;
}

function buildList(arr) {
  var listHTML = '<ol>';
  for (var i = 0; i < arr.length; i+=1) {
    listHTML = '<li>' + arr[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).toLowerCase();
  if (response === answer) {
    correctAnswers +=1;
    correct.push(question);
  } else {
    incorrect.push(question);
  }
}

html = "You got " + correctAnswers + " question(s) right.";
html += '<h2>You got the following questions correct:</h2>';
html += buildList(correct);
html += '<h2>You got the following questions incorrect:</h2>';
html += buildList(incorrect);

print(html);