Deflation is just as bad as inflation so the average inflation rate is meaningless.

It’s less obvious, but the point of currency isn’t simply to have more value stored as currency which changes nothing. It’s to facilitate the exchange of goods over time. During inflation sellers are reluctant and during deflation buyers are reluctant, both of which are problems.

And while it’s easy to think of yourself as a buyer or a seller every transition requires both in exactly equal amounts.