text: import matplotlib.pyplot as plt
  from collections import Counter
  
  grades = [83, 95, 91, 87, 70, 0, 85, 82, 100, 67, 73, 77, 0]
  decile = lambda grade: grade//10*10
  histogram = Counter(decile(grade) for grade in grades)
  
  plt.bar([x for x in histogram.keys()],
          histogram.values(),                # korrekte Höhe
          8)                                 # Breite 8
  
  plt.axis([-5, 105, 0, 5])
  plt.xticks([10*i for i in range(11)])
  plt.xlabel("Dezil")
  plt.ylabel("Anzahl Studenten")
  plt.title("Verteilung der Prüfungen")
  
  plt.show()