게 줄어들다

shrink or drop noticeably

A degree adverb plus 줄어들다, to get smaller or decrease: sharply, clearly, greatly, subtly. What shrinks in these lines ranges from a blanket that came back smaller to a diet, a death rate, a population and the scale of stimulus. 줄어들다 is something shrinking on its own; 줄이다 is what you do to make something smaller.