Spreading your seed

In my numerous readings that amount to a whole lot of information about nothing, I came across, what I personally think, is quite possibly the most fertile man that ever lived. Emperor Kangxi 1662 - 1722, China, had 36 sons and 20 daughters. He lived for a grand total of 68 years in which he produced 56 children. Now think about this for a minute: that means he did not reproduce for only 12 years in his life(assuming he had one child per year). It is almost as though he started reproducing as soon as he was biologically capable. Looking at it from the female perspective: Kangxi had 4 wives, who bore him the 56 bundles of joy. In other words, 14 kids per wife. Asuming the average lifespan of a woman in 18th century China was 70 years, women reached menopause at the age of 50,were capable of having and keeping a baby alive from the age of 13, and the king lost interest in them after the age of 35, we are left with a grand total of 22 years in which an empress/concubine could be pregnant. This means that all of his wives were pregnant 63% of time they could be pregnant. Wow! This, ladies and gentlemen, was a busy man.