How much coolant level drop do you experience after coolant replacement?

As some air goes out of the cooling system, the level drops.

In my case, I added almost 1 liter in a couple of months to compensate for the the level drops. 1992 300D. 275 k miles.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.