Medicare spending isn’t just lower than experts predicted a few years ago. On a per-person basis, Medicare spending is actually falling.

If the pattern continues, as the Congressional Budget Office forecasts, it will be a rarity in the Medicare program’s history. Spending per Medicare patient has almost always grown more rapidly than the economy as a whole, often by a wide margin.

Health economists call that difference “excess cost growth.”

Lately, though, some have taken to using the unwieldy phrase “negative excess cost growth.”

This year, Medicare, which covers those 65 and older and people with disabilities, will spend about $11,200 on average for every person enrolled in the program. By comparison, it spent $12,000 three years ago, in inflation-adjusted dollars. The Congressional Budget Office forecasts that the number will fall below $11,000 by 2017 and stay below this year’s number until 2020.