Comparison between the 
correspondig maxima, 
in year, Stockholm 1889 tide gauge
=============================
ObsPer     DerPer
-----------------------------
 42.667    46.545
 28.444    26.947
 18.963    18.963
  9.660     9.660
  8.533     8.678
  7.758     7.758
  6.400     6.400
  5.626     5.689
  4.531     4.531
  4.197     4.197
  3.631     3.631
  3.282     3.282
  3.103     3.103
  2.994     2.994
  2.844     2.844
  2.485     2.485
  2.073     2.073