text: The plot shows a statistic: Permutations -> Integers on permutations at most 6.
  
  These are ordered lexicographically (on the x-axis) for each length, so the list starts with [1],[1,2],[2,1],[1,2,3],[1,3,2]). The y-axis shows the statistic values.
  
  Q: Which statistic is shown in the plot ?