@Override
  public double metricValue() {
    double noDocs = this.docs.size();
    double noDocsWithoutEndorcement = 0.0;

    for (DigitalSignature ds : this.docs.values())
      noDocsWithoutEndorcement += (ds.fullEndorcement()) ? 1 : 0;

    statsLogger.info(
        "DigitalSignatureUsage. Dataset: {} - Total # Documents : {}; # Documents without Endorcement : {};",
        EnvironmentProperties.getInstance().getDatasetURI(),
        noDocs,
        noDocsWithoutEndorcement);

    return (noDocsWithoutEndorcement / noDocs);
  }