prepositions - Difference between (in / for / ∅ / during / over) the (past / last) three years

Microsoft has steadily improved its operating cash flows in the past three years.

Microsoft has steadily improved its operating cash flows in the last three years.

Microsoft has steadily improved its operating cash flows for the past three years.

Microsoft has steadily improved its operating cash flows for the last three years.

Microsoft has steadily improved its operating cash flows for the past three years. ("for" omitted)

Microsoft has steadily improved its operating cash flows for the last three years. ("for" omitted)

Microsoft has steadily improved its operating cash flows during the past three years.

Microsoft has steadily improved its operating cash flows during the last three years.

Microsoft has steadily improved its operating cash flows over the past three years.

Microsoft has steadily improved its operating cash flows over the last three years.

Which of them are idiomatic and preferred? Are they interchangeable?