-if (time <= 120) set xtics 0.5 nomirror;
-if (time <= 300) set xtics 1 nomirror;
-if (time <= 900) set xtics 2 nomirror;
-if (time <= 1200) set xtics 3 nomirror;
-if (time <= 1800) set xtics 5 nomirror;
-if (time > 1800) set xtics 10 nomirror;
+#set xtics based on elapsed time
+set xtics 1 nomirror
+if (time > 300) set xtics 1 nomirror;
+if (time > 900) set xtics 2 nomirror;
+if (time > 1800) set xtics 5 nomirror;