static double sortedPercentage(Cl l) {
  new Scorer scorer;
  Iterator it = iterator(l);
  if (it.hasNext()) {
    O a = it.next();
    while (it.hasNext()) {
      O b = it.next(); 
      scorer.add(cmp(a, b) > 0);
      a = b;
    }
  }
  ret scorer.percentScore();
}