private double queryFractionOfMax(Instant now) {
        if (queryFractionOfMax != null) return queryFractionOfMax;
        return queryFractionOfMax = clusterTimeseries().queryFractionOfMax(scalingDuration(), now);
    }
Returns the average query rate in the scaling window as a fraction of the max observed query rate.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/autoscale/ClusterModel.java