How to center axis in tchar component?

Question

Delphi

Hello, we are dealing with a tChart component in Delphi 7.
There is an uneven sinusoid with an amplitude, for example, from -10 to +20. Values ​​can be different, but not symmetrical (-3/+40), (+10/+50).
How to center the axis of the sine wave (at level 10)?
The option is not suitable, as it sets the axis to 0, not 10cht1.BottomAxis.PositionPercent := 50;