Does the ratio of daylight change from year to year?
I don't think it's possible to have a change in the ratio of day to night when averaged on a yearly basis.  To do so would require either a nonlinear change in the Earth's rotation or a significant shift in the polar axis tilt within a year.
If the rotation were simply slowing down over time, the year-averaged ratio would be the same every year (only the number of days in a year would change).  Similarly, the only way a polar tilt could cause a change would be if the change in angle occurred at some (sinusoidal) rate not an integral ratio of the orbital period (year).
Either of those putative mechanisms can only change the per-year ratio by producing a day/night ratio in "summer" that is not the inverse of the "winter" ratio, and producing a different non-inverse the following year.  (I'm oversimplifying a bit, since the elliptic orbit produces a repeatable asymmetry in the Sun's zenith pattern).