diff --git a/bot.go b/bot.go
index e038ab1..f1f2660 100644
--- a/bot.go
+++ b/bot.go
@@ -1050,23 +1050,22 @@ func botGraphValueDelta(m *tb.Message) {
 	}
 
 	for coID, v := range vals {
-		if len(v) <= 3 {
-			delete(vals, coID)
-		} else {
-			v0 := v[0].Y
-			v1 := v[1].Y
-			v2 := v[2].Y
-			for i := 3; i < len(v); i++ {
-				v0 = v1
-				v1 = v2
-				v2 = v[i].Y
-				v[i].Y = (v0+v1+v2)/3 - v1
-				if math.Abs(v[i].Y) > maxVal {
-					maxVal = math.Abs(v[i].Y)
-				}
-			}
-			vals[coID] = v[3:]
+		v2 := make(plotter.XYs, 0)
+		for i := 0; i < len(v); i = i + 3 {
+			v2 = append(v2, v[i])
 		}
+		vals[coID] = v2
+	}
+
+	for coID, v := range vals {
+		v0 := v[0].Y
+		for i := 1; i < len(v); i++ {
+			v[i].Y, v0 = v[i].Y-v0, v[i].Y
+			if math.Abs(v[i].Y) > maxVal {
+				maxVal = math.Abs(v[i].Y)
+			}
+		}
+		vals[coID] = v[1:]
 	}
 
 	if maxVal > 1000000000 {
@@ -1083,7 +1082,7 @@ func botGraphValueDelta(m *tb.Message) {
 	logInfoDebug("botGraphValueDelta : unit set to %s (factor : %f)", unitName, unitFactor)
 
 	for coID, v := range vals {
-		for i := 1; i < len(vals)-1; i++ {
+		for i := 0; i < len(vals); i++ {
 			v[i].Y = v[i].Y / unitFactor
 			if math.IsNaN(v[i].Y) {
 				logInfoDebug("botGraphValueDelta : NaN : %d / %f", coID, v[i].X)
diff --git a/version.go b/version.go
index c63723e..e9b6fa8 100644
--- a/version.go
+++ b/version.go
@@ -1,6 +1,6 @@
 // Code generated by version.sh (@generated) DO NOT EDIT.
 package main
-var githash = "ef7af10"
-var buildstamp = "2021-12-08_13:30:52"
-var commits = "242"
-var version = "ef7af10-b242 - 2021-12-08_13:30:52"
+var githash = "350d7cf"
+var buildstamp = "2021-12-08_14:02:46"
+var commits = "243"
+var version = "350d7cf-b243 - 2021-12-08_14:02:46"