Fix mismatches between format string and arguments
diff --git a/tests/decperf.cxx b/tests/decperf.cxx
index 1d0c80c..5763976 100644
--- a/tests/decperf.cxx
+++ b/tests/decperf.cxx
@@ -211,7 +211,7 @@
   sort(dev, runCount);
   meddev = dev[runCount/2];
 
-  printf("CPU time: %g s (+/- %g %)\n", median, meddev);
+  printf("CPU time: %g s (+/- %g %%)\n", median, meddev);
 
   return 0;
 }