Good find, although that would assume that every hour of the year is equally contributing to revenue. In reality I would think that an hour-long outage in the morning as everyone in N. America (still the largest percentage of reddit users) is reading reddit while waking up/drinking coffee is probably more costly than an hour-long outage while most of those users are asleep.
My first exposure to empty set citations
{} would at least be consistent with python string substitution, but [] doesn't make much sense to me