Yes, in the period of June 20th - July 18th the measurable self-voting was approx. 9% of the reward pool. For comments the measurable self-voting was a minimum of about 35% of the comment rewards (this is likely largely because abusers can now self-vote in only 11 comments a day instead of 44 when the maximum vote went to 2% from 0.5%).

Obviously we can't know the self-voting that is being done between multiple accounts, owned by the same user. On top of that, stellabelle has the same worry that the number will only increase. Imagine when World of Warcraft gold farms discover SteemIt, or worse, that's not going to be pretty.

You can look at my latest post which includes links to all 3 related articles.