Blowfeld, 04C13D9C... is mine & I've had about 2 per day solved for the last 3 days or more, many thanks if that's you! - Much appreciated 
& very interesting about the easier & harder prefixes I wasn't at all aware of that.
You're welcome for what I did: I found 1Tarot78 and 1Hashing. Nothing else for a while. So, there are other vanity miners doing the majority of your work. The 1Tarot78 prefix was extremely lucky, because it was equivalent to some 8-character vanity addresses.& very interesting about the easier & harder prefixes I wasn't at all aware of that.