It seems that Reddit has a 30% chance to be down at any given moment regardless of outside influences. No other AAA website is so badly programmed and so badly managed.
I've had my share of problems with Reddit but it's never seemed to have an undue amount of downtime, and I've been clicking on the old.reddit.com interface about a zillion times per day for close to a decade.
I know you're not being literal with the 30%, but I have found it's uptime to be really good. Especially for a site constantly battling spam/bots/etc.