Wikipedia: Higher Averages Method

The highest averages method is one way of allocating seats proportionally for representative assemblies with party list voting systems.

The highest averages method requires the number of votes for each party to be divided successively by a series of divisors, and seats are allocated to parties that secure the highest resulting quotient or average, up to the total number of seats available. The most widely used is the d'Hondt formula, using the divisors 1,2,3,4... The Sainte-Laguë method divides the votes with odd numbers (1,3,5,7 etc). The Sainte-Laguë method can also be modified, for instance by the replacement of the first divisor by 1.4, which in small constituencies has the effect of prioritizing proportionality for larger parties over smaller ones at the allocation of the first few seats.

Another highest average method is called Imperiali (not to be confused with the Imperiali quota which is a Largest remainder method). The divisors are 2,3,4 etc. It is only used in Belgian municipal elections.

Spain uses the D'hondt method, which is the one most biases to favour large parties, with a 3% threshold at the constituency level and no top-up for overall proportionality.

Nothing is 'mere'. — Richard P. Feynman