Choice of words is a component of subtext, as you hinted at yourself. Below I have hilighted the key action word, which is also an important choice when setting subtext.

"One in 5 people now think" is a positive-sounding construction which lends more statstical weight to the result than an impartial examination of the numbers, and people who scan headlines are far from impartial.

Other constructions are "4 in 5 still support...", or "80% still support", or "20% now think", which are all still mathematically neutral, but the subtext is different.