+/**
+ * Typical priorities we're seeing from other peers right now. Since
+ * most priorities will be zero, this value is the weighted average of
+ * non-zero priorities seen "recently". In order to ensure that new
+ * values do not dramatically change the ratio, values are first
+ * "capped" to a reasonable range (+N of the current value) and then
+ * averaged into the existing value by a ratio of 1:N. Hence
+ * receiving the largest possible priority can still only raise our
+ * "current_priorities" by at most 1.
+ */
+static double current_priorities;