fixed eval script

README.md

@@ -218,7 +218,7 @@ for i in range(10):
     D = D + chunk_metrics["deletions"]
     I = I + chunk_metrics["insertions"]
 WER = float(S + D + I) / float(H + S + D)
-print("WER: {:2f}".format(WER*100).mean())
+print("WER: {:2f}".format(WER*100))
 ```
 
 **Test Result**: 15.80 %