Aromatic Character in Percentage? I was just searching whether Uracil is aromatic or not and in this link$^1$ it is said that (from the abstract):

High-level computational methods were tested for the enthalpy of hydrogenation of uracil, but only with G3 was possible to obtain results in agreement with the experimental ones. It was found that uracil possesses 30.0% of aromatic character in the gaseous phase.

What is the meaning of this sentence? I have only basic knowledge on Aromaticity limited to Huckel's rule and the names of a few aromatic compounds. I didn't expect Aromaticity to be expressed in percentages. Can someone explain why?
Reference

Tiago L. P. Galvão, Inês M. Rocha, Maria D. M. C. Ribeiro da Silva*, and Manuel A. V. Ribeiro da Silva. J. Phys. Chem. A 2013, 117, 28, 5826–5836.
https://doi.org/10.1021/jp404938u
G3 is generally a term used to describe a particular computational model used in calculating molecular bonding in quantum chemistry.  The G refers to Gaussian and 3 is just a third iteration of including additionally complex terms to the molecular orbital calculations being used.  There's a brief discussion on wikipedia, but you'll find more extensive discussion of these types of calculations in Quantum Chemistry text books or directly from the researcher's works just an example, a G3 Theory site.
Aromaticity can actually be measured quantitatively via Aromatic ring current and calculated with [NICS] nucleus-independent chemical shift.  The wikipedia article included a link to a paper describing the quantitative scale.  It's just a way of saying how aromatic is the molecule compared to another (call it a standard / perfect example molecule.)  The problem with such relative standards is there may always be one that exceeds the standard, so you could potentially end up with results larger than 100%.