Update stats.class.php

Fix div/0 warnings

htdocs/core/class/stats.class.php

@@ -384,16 +384,16 @@ abstract class Stats
 				$row = $this->db->fetch_object($resql);
 				$result[$i]['year'] = $row->year;
 				$result[$i]['nb'] = $row->nb;
-				if($i>0 && $row->nb) $result[$i-1]['nb_diff'] = ($result[$i-1]['nb'] - $row->nb) / $row->nb * 100;
+				if($i>0 && $row->nb>0) $result[$i-1]['nb_diff'] = ($result[$i-1]['nb'] - $row->nb) / $row->nb * 100;
 				$result[$i]['total'] = $row->total;
-				if($i>0 && $row->total) $result[$i-1]['total_diff'] = ($result[$i-1]['total'] - $row->total) / $row->total * 100;
+				if($i>0 && $row->total>0) $result[$i-1]['total_diff'] = ($result[$i-1]['total'] - $row->total) / $row->total * 100;
 				$result[$i]['avg'] = $row->avg;
-				if($i>0 && $row->avg) $result[$i-1]['avg_diff'] = ($result[$i-1]['avg'] - $row->avg) / $row->avg * 100;
+				if($i>0 && $row->avg>0) $result[$i-1]['avg_diff'] = ($result[$i-1]['avg'] - $row->avg) / $row->avg * 100;
 				// For some $sql only
 				if (isset($row->weighted))
 				{
 				    $result[$i]['weighted'] = $row->weighted;
-				    if($i>0 && $row->weighted) $result[$i-1]['avg_weighted'] = ($result[$i-1]['weighted'] - $row->weighted) / $row->weighted * 100;
+				    if($i>0 && $row->weighted>0) $result[$i-1]['avg_weighted'] = ($result[$i-1]['weighted'] - $row->weighted) / $row->weighted * 100;
 				}
 				$i++;
 			}