My question today isn't very intelligent One of the books I have (Marshall Cavendish Education) suggests the following order of arranging adverbs of indefinite frequency (and expects learners to do so):

always (100%) - often (100-80%) - usually (80-60%) - sometimes (50-40%) - occasionally (20-10%) - never (0%)

It's not actually about percentage, but about which adjective implies greater frequency - often or usually. The authors think it's often.

Another book (Macmillan) claims it's usually that implies greater frequency compared with often. Michael Swan claims nothing, but lists the adjectives in the following order: always -- ever -- usually --normally -- often.. ...and so on.

It's not that important, but it got me thinking. I suspect it's one of those things some people disagree on.
I'd love to hear your thoughts on this.

Thank you.