Hmm, honestly to me this is still a big percentage. Keeping in mind the amount of SP a few whale accounts hold, there's only so much left to be spread out over the rest of the accounts. If we take the biggest whales out of the equation, bid bots own a considerable amount of SP.
Ofcourse, like you said, Trending has always been crap, because not all of the bigger whales like to spread their votes around much.
I'll still say I hate bid bots though ;-)
This would change a lot if we got the v.20 update, more accounts means they are spread more thin.