Setting Chart Axis Minimums and Maximums 
The Trend Chart module type is selected in the Add/Edit Dashboard Panel dialog box.
In the Add/Edit Dashboard Panel dialog box, click Advanced to display the Advanced dialog box.
In the Left Y Axis Minimum text box, specify the lowest value to chart on the left Y-axis.
In the Maximum text box, specify the highest value to chart on the left Y-axis.
If you are displaying a secondary Y-axis, then in the Right Y Axis Minimum text box, specify the lowest value to chart on the right Y-axis.
In the Maximum text box, specify the highest value to chart on the right Y-axis.
The chart shows all points associated with the left Y-axis starting at the left Y-axis minimum number. If any points are lower than that number, they appear to start at the minimum number.
All points associated with the left Y-axis now end at the left Y-axis maximum number. If any points are higher than that number, they appear to end at the maximum number.
The chart shows all points associated with the right Y-axis starting at the right Y-axis minimum number. If any points are lower than that number, they appear to start at the minimum number.
All points associated with the right Y-axis now end at the right Y-axis maximum number. If any points are higher than that number, they appear to end at the maximum number.