Complex sentence: Membership is split fairly equally among the sexes, and the members of the QM Union have outnumbered those of the GU Union at student level for many years, however it remains dwarfed by the GU Union's 9,000 life members.
Split into simpler sentences: Membership is split fairly equally among the sexes, and the QM Union has maintained high membership levels for many years. While claiming higher numbers of student members, the QM Union remains dwarfed by the GU Union's 9,000 life members.