Does anyone know what the consumption number refers to? Daily? Weekly? Yearly?

Annual consumption, it declares so when you hover over it.

Yearly. See the tooltips in table headers.

I looked at the "all" timeline graph for France here [1]. Could someone explain why the big jump ~2012 ?

[1] https://agsi.gie.eu/data-overview/graphs/FR

The "added" capacity is close to Storengy's total capacity.

My guess is that the chart is missing pre-2012 data on those sites.

Germany: stored 239.64, consumption per year 905.30 ⇒ 239×12/903 ≃ 3.17 months

Spain: stored 32.99, consumption per year 338.99 ⇒ 32×12/903 ≃ 0.42 months

However, the “Stock/Cons” column, annotated with “Filling level compared to annual consumption”, shows this:

Germany: 26.47 ⇒ 26.47×12 ≃ 317.64 months

Spain: 9.73 ⇒ 9.73×12 ≃ 116.76 months

What did I misunderstand?

Stock/Cons is in percent, if you divide your 317 months by 100 you get the expected result.

Ah, thanks! I thought it was a ratio. I should have noticed the % symbol in the column header.