Complex sentence: From its inception the Mafdal maintained an almost constant number of 12 members of the Israeli Knesset, until 1981 when it shrank to 6 and has never fully recuperated.
Split into simpler sentences: From its inception until 1981 the Mafdal maintained an almost constant number of 12 members of the Israeli Knesset. In 1981 it shrunk to 6 and has never fully recuperated.