This is already implemented since about a week 
That’s why there’s now a “weighted” rating (visible to the author) which is used to calculate which icons to show. The percentile (a percentile of “5 %” means, that your story is in the top 5% for that rating) is directly dependent on that weighted rating.
20%: simple icon
5%: silver icon
1.25%: gold icon
See also the discussion here which lead to this implementation: