No, you can't mark it as January through December if that business did not exist during all of that time.
If you were not ELGIBLE for health insurance through your W-2 employer, you can count August (but you can't count Sept or Oct if you were eligible for insurance for those months).
It still doesn't make sense why that would be lower though. And without being able to see your tax return, unfortunately I can't really figure that out for you.
