function interpretTwoDigitYear(year) {
  var thisYear = new Date().getFullYear();
  var thisCentury = thisYear - thisYear % 100;
  var centuries = [thisCentury, thisCentury - 100, thisCentury + 100].sort(function (a, b) {
    return Math.abs(thisYear - (year + a)) - Math.abs(thisYear - (year + b));
  });
  return year + centuries[0];
}
Give this function a 2 digit year it'll return with 4.

@example
    interpretTwoDigitYear(15);
    // => 2015
    interpretTwoDigitYear(97);
    // => 1997
@param {number} year
@returns {number}
@private