Popularity rank
A blog's popularity rank is calculated using the number of unique readers each day
for the past seven days. For example, if the popularity rank is 10, that means there
are 9 blogs that are more popular than that blog.
"Unique readers" means that no matter how often someone reads a blog, they are only
counted once when the popularity rank is calculated. This ensures fair rankings
by allowing each person to only "vote" once.
