Helium abundance

[vladivostok]

Hi,

Here is an info I don't manage to obtain from anywhere so far !!
What is the "best-estimate" of the Helium abundance (the He/H ratio) in the interstellar medium of galaxies in the nearby Universe and at high redshift?

I know the primordial He abundance is Y = 0.24 but what is the value for the ISM of galaxies?

Does anybody know that? any reference please?

Thanks !

[Drakkith]

I venture a guess that is about the same ration. Maybe a little more skewed towards helium now, but mostly still the same.