How do I calculate the lowest point?
Well, for what it's worth:
in the january-graph we see at the same hight as now, that the lowest point over there is 12700
the lowest point of the tail over there is 9200.
I have in january a scale from 100 to 100 (so 7200 / 7100 / 7000 etc.)
From 12700 to 9200 is ~35 steps.
The lowest hight now overhere is ~7520
The scale from now is at my chart 40 to 40 (7520 / 7480 / 7440 etc.)
so ==> ~35 x 40 = 1400
That means 7520 - 1400 = 6120 !
I hope it works that way.
We will see!