diff --git a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartAggregatorForIntervals.java b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartAggregatorForIntervals.java
index 8b44273..7caa2bb 100644
--- a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartAggregatorForIntervals.java
+++ b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartAggregatorForIntervals.java
@@ -17,6 +17,8 @@ import org.lucares.recommind.logs.GnuplotAxis;
 
 public class BarChartAggregatorForIntervals implements CustomAggregator, IndexedAggregator, BarChart {
 
+    private static final double SPACE_BETWEEN_BARS = 0.6;
+
     private final Path tmpDir;
 
     private Long index = null;
@@ -77,13 +79,14 @@ public class BarChartAggregatorForIntervals implements CustomAggregator, Indexed
     @Override
     public String asCsv() {
         final StringBuilder csv = new StringBuilder();
+        final boolean isMiddleSeries = getIndex() == numberOfDataSeries / 2;
 
         int offset = 0;
         for (final String bucketId : bucketIds()) {
             final long count = buckets.get(bucketId).get();
-            csv.append(getIndex() + 0.5 + offset);
+            csv.append(offset + getIndex() * SPACE_BETWEEN_BARS + 0.5);
             csv.append(",");
-            csv.append(bucketId);
+            csv.append(isMiddleSeries ? bucketId : "");
             csv.append(",");
             csv.append(count);
             csv.append("\n");
@@ -131,8 +134,8 @@ public class BarChartAggregatorForIntervals implements CustomAggregator, Indexed
             final long count = buckets.get(bucketId).get();
             final String label = String.format("set label at %s %f, %d '%s' center front offset 0,0.3\n", // front
                     xAxis == GnuplotAxis.X1 ? "first" : "second", //
-                    getIndex() + 0.5 + offset, //
-                    count, //
+                    offset + getIndex() * SPACE_BETWEEN_BARS + 0.5, // x-axis position of the label
+                    count, // y axis position of the label
                     String.format(Locale.US, "%,d", count));
 
             result.append(label);
diff --git a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartHandler.java b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartHandler.java
index 97baeaf..4667e3a 100644
--- a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartHandler.java
+++ b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/BarChartHandler.java
@@ -42,7 +42,6 @@ public class BarChartHandler extends AggregateHandler {
         result.setType(Type.Group);
         result.setAxis(getxAxis());
         result.setTicsEnabled(false);
-        // TODO revert next two lines
         result.setFrom("0");
 //        result.setTo(String.valueOf(dataSeries.size()));
 
diff --git a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/Interval.java b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/Interval.java
index 0b68032..ba83834 100644
--- a/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/Interval.java
+++ b/pdb-plotting/src/main/java/org/lucares/pdb/plot/api/Interval.java
@@ -62,15 +62,15 @@ public class Interval {
     private String toDateFormatForBucketer(final IntervalTimeUnit intervalTimeUnit) {
         switch (intervalTimeUnit) {
         case MINUTE:
-            return "yyyyMMddHHmm";
+            return "yyyy-MM-dd HH:mm";
         case HOUR:
-            return "yyyyMMddHH";
+            return "yyyy-MM-dd HH";
         case DAY:
-            return "yyyyMMdd";
+            return "yyyy-MM-dd";
         case WEEK:
-            return "YYYYww"; // use week based year! Otherwise intervals over the year boundary will be wrong
+            return "YYYY-ww"; // use week based year! Otherwise intervals over the year boundary will be wrong
         case MONTH:
-            return "yyyyMM";
+            return "yyyy-MM";
         case YEAR:
             return "yyyy";
         default: