I was looking at the page on the day/night cycle, and it suggests that the numbers should be as follows:

Type - Game Ticks - Ratio of a day
Full day - 24966 - 1
Day - 12482 - 0.5
Night - 3994 - 0.16
Dawn or Dusk - 4245 - 0.17

When I put these calculations in the formula, I got a ratio of 0.92, or ...