Which of these Words is Sung the Most Times?

Question: In these respective songs, which of the words is sung the most amount of times? Earthquake in Labrinth’s song Earthquake, Firework in Katy Perry’s song Firework, Baby in Justin Bieber’s hit Baby or Bonkers in Dizzee Rascal’s hit Bonkers?

The answer is Baby in Justin Bieber’s hit single. He actually sings it 56 times in total.