Get bucket item count in Couchbase .NET client

I'm just getting started experimenting with Couchbase (v1.8) using the .NET client. I can't figure out how to get a basic count of items I've stored in the default bucket. My storage code is pretty simple:

var client = new CouchbaseClient();
var session = new Session { SessionId = "session_1234" };
client.Store(StoreMode.Add, sessionId, session);

But now I just want to get a count of all the sessions I've stored in my couchbase bucket. I've looked at the .NET API docs and can't seem to find a way to do this.