Spain 1479 to 1833, 14 kings 354 yrs. Average 25.
Portugal 1102 to 1826, 27 kings 724 yrs. Average not 21.
Denmark 1157 to 1839, 28 kings 672 yrs. Average 25.
Russia 1722 to 1825, 9 sover. 103 yrs. Average 11-1/2 yrs.
Total: 294 sovereigns, 6085 years; being an average of about 20-2/3,
although including the latest times. It is evidently unfair to take
recent times only, as Hales, Clinton, &c. do.