How did we find the composition of the universe when our observation of it is limited

The standard model of cosmology indicates that the total mass–energy of the universe contains 4.9% ordinary matter, 26.8% dark matter and 68.3% dark energy.

For the standard cosmological model, the observable horizon has a total comoving volume of $12150$ cubic Gigaparsecs. That is our potentially observable universe, and is known as the Hubble volume. The deepest observation with an optical telescope is the Hubble Ultra Deep Field, which has confirmed galaxies out to redshift of $10$. Plugging this to the cosmological model, we get a comoving volume within this redshift of $3776$ cubic Gigaparsecs, which corresponds to roughly 30% of the Hubble volume.

Hence when we can observe only $\approx{27.8}$% of our universe how can we Calculate the percentage contribution of matter? With that said how do we calculate the percentage contributions of dark matter and dark energy?

Note: Related question: How do people calculate proportions of dark matter, dark energy and baryonic matter of the universe?. This question is to do with how the actual calculations were done, but my question is to do with how could these calculations be done when our observation of the universe is limited.

• The obvious approach is 'look at the bit of the universe we can see and assume that the bits we can't are similar'. This is a reasonably straightforward application of the cosmological principle. – tfb Nov 28 '16 at 17:13