I detect a different pattern among the under-20's. The more religious groups tend to have the higher birthrates and therefore in the future the 42% who are 'secular' may actually decrease. Secular zionism began as a rejection of traditional Judaism which came to be associated with oppression in Eastern and Central Europe. Secular meaning anti-religious has evolved to secular meaning 'let me just get on with my life'. The fact that secular Jews attend shul on the High Holy Days and make a seder and light Chanukah candles suggests they are not completely secular. Three generations back 'secular' Jews had Yom Kippur banquets with mixed dancing, thank G-d a thing of the remote past!
Kerry: Pollard's parole not related to Iran deal (Reuters)
from the article: Poll: Fewer than half of Israelis see themselves as secular