Complex sentence: The vast majority, 88.35% of households in the top quintile were family households with 80.8% of all households in this quintile being composed of married couple families that featured a mean of two income earners.
Split into simpler sentences: The vast majority, 88.35%, of households in the top quintile were family households. Furhtermore 80.8% of all households in the top quintile were composed of married couple families that featured a mean of two income earners.