ecoinvent - EF v3.1 // Normalization & weighting is empty ?

Question

Hi.

I use ecoinvent v3.9.

I see in my database that the impact assessment method 'ecoinvent - EF 3.1' (and basically all others) are empty. I can create a set of normalization and weighting.

So I have 2 questions :

- Why is it empty ?

- If I have to create a set, where do I get the data from ? 

Thank you for your help 

Kevin