Complex sentence: It has a population of 8,607 in 2000, down from 12,172 in 1990 because of annexations by Middletown, and of those 8,607, only 2,335 live in the unincorporated portion of the township.
Split into simpler sentences: It has a population of 8,607 in 2000, down from 12,172 in 1990 the decrease thanks to annexations by the city of Middletown. Of those 8,607, only 2,335 live in the unincorporated portion of the township.