Well, the scores I give are somewhat relative. As in, an 8/10 means that an episode is well above average next to other episodes of the same show. But if you took an 8/10 on Voyager and compared it to an 8/10 on say TNG or DS9, the latter episodes would win out in my favor.
But you started rating the episodes out of 10 before you knew what the quality of the average episode was really like so does this new rating idea you're now presenting (which I find confusing and really don't like that sfdebris uses it) is only relevant to very recent ratings?
Anyway I don't think the quality of season 6 and season 7 are suddenly much higher rather that you've had a break and are able to now enjoy Voyager for what it is rather than be bogged down by the frustration of expecting better in the former seasons. If you ever rewatch seasons 1/4/5, you'll probably find they're really not that different in quality from 6 and 7.
The same thing happened with me, on a rewatch when my bitterness towards Voyager subsided and learned to enjoy it on it's own merits.