Show how the last active breakdown evolved over time.

def GetReportData(self, get_report_args, token):
    """Show how the last active breakdown evolved over time."""
    report = rdf_report_plugins.ApiReportData(
        representation_type=rdf_report_plugins.ApiReportData.RepresentationType
        .LINE_CHART)

    series_with_timestamps = client_report_utils.FetchAllGraphSeries(
        get_report_args.client_label,
        rdf_stats.ClientGraphSeries.ReportType.N_DAY_ACTIVE,
        period=rdfvalue.Duration("180d"))

    categories = {}
    for timestamp, graph_series in sorted(iteritems(series_with_timestamps)):
      self._ProcessGraphSeries(graph_series, timestamp, categories)

    graphs = []
    for k, v in iteritems(categories):
      graph = dict(label=k, data=v)
      graphs.append(graph)

    report.line_chart.data = sorted(
        (rdf_report_plugins.ApiReportDataSeries2D(
            label=label,
            points=(rdf_report_plugins.ApiReportDataPoint2D(x=x, y=y)
                    for x, y in points))
         for label, points in iteritems(categories)),
        key=lambda series: int(series.label.split()[0]),
        reverse=True)

    return report