Gas consumption based on counter: Set constant offset (add m³ already consumed)

Hi everyone,

I have created a counter device for my gas meter and it works well.
Based on this data I have created Utility Meter for Day, Month and year.
Because I just started, all three of them are low.

So, I would like to add the consumed m³ this year to the yearly consumption.
If I set the state as required using the development tools, it will be reset if triggered / updated by the counter (as expected).

How to set a constant offset to the value of the Yearly gas consumption which persists?
Any suggestion is very welcome