As you see from the responses, there's a huge range of miles ridden, and speed, and there's no universal right or wrong number. If you're enjoying being on the bike, you're doing it right.
My weekly 100 miles is not random. I discovered that if I ride more than that, I feel really tired all the time. Less than that, well it's okay if I do a little less, but a lot less and I'm afraid of losing fitness, plus I like having something to aspire to. At this rate, I feel really great, and I have energy.
Speed I've given up caring about. I suspect I'm not slow because I pass more people than pass me, but it really doesn't matter if I'm fast (although I admit to occasionally riding so hard I almost puke, just to try to keep someone from dropping me). 
Most of all, have fun. If it's not fun, why bother?
'02 Eddy Merckx Fuga, Selle An Atomica
'85 Eddy Merckx Professional, Selle An Atomica
'10 Soma Double Cross DC, Selle An Atomica
Slacker on wheels.