private void writeIntervalSummaryDataPerTest(Map<Test, StatisticsSet> intervalStatisticMapPerTest, boolean lastCall) {
		if (intervalStatisticMapPerTest.size() > 1) {
			for (Entry<String, StatisticExpression> each : getExpressionEntrySet()) {
				if (isPerfTestInterestingStatistics(each.getKey())) {
					for (Entry<Test, StatisticsSet> entry : intervalStatisticMapPerTest.entrySet()) {
						if (lastCall) {
							StatisticsSet value = entry.getValue();
							writeReportData(each.getKey() + "-" + entry.getKey().getNumber() + "_"
									+ entry.getKey().getDescription().replaceAll("\\s+", "_") + REPORT_DATA,
									formatValue(getRealDoubleValue(each.getValue().getDoubleValue(value))));
						} else {
							writeReportData(each.getKey() + "-" + entry.getKey().getNumber() + "_"
									+ entry.getKey().getDescription().replaceAll("\\s+", "_") + REPORT_DATA, "null");
						}

					}
				}
			}
		}
	}
Write the interval summary data per each test. This is activated only
when there are more than 1 registed test.

@param intervalStatisticMapPerTest statistics map
@param lastCall                    true if it's the last call of consequent call in a single
                                   sampling
ngrinder-core/src/main/java/net/grinder/SingleConsole.java