Soundhole sizes

If this is a stupid, obvious question, let me know.
Why is the soundhole on ukuleles smaller, in relation to body size, than the soundhole on the average guitar? Or is it an optical illusion?
And if that is so, what is the benefit of a larger soundhole on a uke?

Not answering your question with facts, I can only say that the ukes I've made with a larger soundhole have a more trebly and plinky sound. The ones with smaller sized holes are less trebly (I cannot write more bassy, they're still ukes) and plunky sound.

I like them smaller.

What Sven said!
Again, no facts here, but the uke body is obviously smaller so there is less air to move inside, so it follows that less room is needed for said air to escape? Just a theory. I'm sure a clever person will be along soon with a more scientific answer.

I've always thought that a smaller sound hole did two things.

1) slightly increased the volume (as in cm or inches cubed) of air inside, thereby creating a lower resonant frequency and increasing bass response.
2) increased the surface area of the top (again slightly) and it's resonant frequency and ability to move said air in chamber.

It must have a little bit of effect on flexibility as well. I don't know if I'm right though. I seem to prefer ukes that have had a smaller sound hole but that can't be the only factor.

I think this was discussed previously.
http://www.ukuleleunderground.com/forum/showthread.php?38651-Soundhole-Diameters