text: var puzzles = db.puzzle;
  
  modified = 0;
  
  puzzles.find({
    'vote.ratio': {$exists: false}
  }).forEach(function(p) {
    puzzles.update({
      _id: p._id
    }, {
      $set: {
        "vote.ratio": NumberInt(100*(p.vote.up - p.vote.down)/(p.vote.up + p.vote.down)),
        "vote.nb": NumberInt(p.vote.up + p.vote.down)
      },
      $unset: {
        'vote.sum': true
      }
    });
    modified += 1;
  });
  
  print(modified);
  