it is mostly made of space
well the universe is endless, but the universe is made up of many galaxies, and galaxies are made of planets and stars and dust etc.
empty space
Bode's universe can not be measured. The reason the universe can not be measured is because it is made up of all the matter, intergalactic space, galaxies, stars and planets.
the universe is made up of galaxies
In one way, that's a pretty good answer. More pointedly, the universe is mostly empty void. The galaxies seem to be the most common large scale structures in the universe, but they are a few shakes of a pepper shaker over three rooms of white carpet, as it were.
universe is largest. universe is made up of billions of galaxies.
The universe is mostly made up of dust, stars and empty space. The universe is so large and grows daily, so that means that even more empty space is added to the universe daily.
This is mostly theory, Galaxies are made of billions of stars. For some reason Galaxy's hold on to their stars. We do not really understand how galaxy's can yet hold their form like this. Our math so far has trouble with making sense of this. When comparing one galaxy to another, size becomes so large words are hard to describe the distance of space. There is an an incredible amount of space between everything out there. What is the distance between galaxies, why is it there, The expanding universe is trying to explain the growing spaces between galaxies yet the galaxies appear to stay bound to themselves.
Galaxies are made mostly of empty space. The most common elements however are hydrogen and helium.
Much more than that, actually. The number of galaxies in the OBSERVABLE Universe is at least 1011.
The universe isn't s fabric. The universe is mostly just vaccum, which is like air but with absolutley no particles. My guess is that the 'fabric' of the universe is space-time.
It's not that the universe is made of up "galaxies" and that an exact "percent" can be given in the way that you are thinking, but the Hubble Telescope estimates that the universe is actually occupied by hundreds of billions of galaxies (maybe even more!).