Phrasing a proportional declines in welfare transfers? Every year social welfare has increased in my study, but these increases as a percentage of this total welfare transfer have fallen every year. I want to say that the social welfare transfer increase as a percentage of this total welfare transfer has been declining since 2000, but I can't think of a non-clunky way to phrase this, is there a technical term I could use?

You could say that the increases have been _decelerating_.

Mathematically, the amount of social welfare, as a function over time, has been increasing (hence, the first derivative of that function would be positive), but the rate of that increase has been decreasing (so the second derivative is negative)