MAGNETIC VARIATION Which one to choose?

Which magnetic variation should I choose for the custom ILS of revisited airports? On the ASOBO BGL for example LIRH gives me 1 ° of magnetic variation, on Navigraph it gives me 2 ° of magnetic variation, on NOAA it gives me 3° 54’ of magnetic variation. I guess they refer to different dates. Which should I choose? the recent NOAA? Or is it the same or one or the other? If you have an explanation or a suggestion I would be enormously grateful.
A greeting

Hi Paolo,
either you take the magvar from the AIP, or you calculate the magvar for the ILS by yourself (difference between true and magnetic heading).

The benedit on the own calculation is, that you’re independent of any source, year, …

Hope that helps

Thanks Richard for the reply, so it is very comfortable for sure. I wanted to ask you why I cannot comfortably align the ILS to the central axis of the runway. For example I have a runway with a physical Earth inclination of 140.456 ° and a Magnetic Declination of 2.5 ° E. My HD referred to the ILS should theoretically be 140.456 - 2.5 = 137.956 °. To insert the magvar in the ILS line I have to do for MSFS2020 360 - 2.5 = 357.5 ° and the HD ILS at 137.956. If instead I want to have an HD of 138.0000 I have to do 140.456 - 138.0000 = 2.456 ° of Magnetic Declination and I will write 360 ​​- 2.456 = 357.544° of magvar in the ILS line having an HD of 138.0000.
Why do I never automatically get the perfect alignment (+/- 20, 30 cm) to the central axis of the Runway? Is this an ASOBO problem? Where can I go wrong? The fact is that I find myself correcting either the magvar or the HD trying and retrying the best angle, with much disappointment. Thanks again for the support.
A greeting.

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