Update VOCDataset.py (open-mmlab#7064)

Author: jbwang1997

mmdet/datasets/voc.py

@@ -92,6 +92,7 @@ def evaluate(self,
                 mean_aps.append(mean_ap)
                 eval_results[f'AP{int(iou_thr * 100):02d}'] = round(mean_ap, 3)
             eval_results['mAP'] = sum(mean_aps) / len(mean_aps)
+            eval_results.move_to_end('mAP', last=False)
         elif metric == 'recall':
             gt_bboxes = [ann['bboxes'] for ann in annotations]
             recalls = eval_recalls(