Here are some depressing numbers about agents, taken from my own records. With extra math!
I keep careful track of all the agent queries I send so I won't accidentally send the same project to the same agent twice. I give all agents about four months to respond, at which point I mark them down as nonresponders (and of course change that if any responses trickle in late). Back in July I brought the table up to date and indicated that the overall nonresponse rate was almost precisely 1/3--that is, 22 out of 65 agents had never responded one way or another to my queries.
That was before I started querying for Trickster Society. Keep in mind that I never re-query a nonresponder, and I'm also cautious about the agents I do query. I research them all carefully and make sure they're open for queries, that they're interested in the genre I'm querying, and that they don't have a reputation for not responding.
Even so, according to my records my nonresponder rate is now up to 42%. Jeez louise, that's getting perilously close to half of all agents who aren't even professional or courteous enough to hit reply and type "Not for me, thanks."
And don't even try to whine that you're too busy to respond, agents. If you're that busy, you have no business being open to queries.
I really hate the agent-querying side of writing. The only thing more depressing is the small-publisher-querying side of writing, because once you're to that point it means that A) all the agents have said no (or not responded) and B) all the big commercial publishers who take non-agented work (all four of them) have said no too.
Yup, I've got the after-holidays, mid-winter, too-many-hyphens blues.
EDIT: I rechecked my figures and the actual nonresponse rate is 36%. Please subtract 6% of the bitchiness from this post.