Table:  Gross Solar and Primordial Cosmic Compositions by Mass Fraction
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  Substance  Traditional  G-1998   A-2009    Primordial
               Solar      Solar    Solar       Cosmic 
              Fiducial                        Fiducial
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  H             0.73      0.7120   0.7154     0.75 
  He            0.25      0.2701   0.2703     0.25 
  Z             0.02      0.0180   0.0142     10**(-3) (counting D, He-3, 
                                                        and Li-7 as a metals)
                                              10**(-9) (counting Li-7 only 
                                                        as a metal)
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1. The solar composition in the Table is the calculated primordial solar nebula composition, NOT the composition of the present-day solar photosphere which has been altered by transport processes in the Sun.
2. Fiducial here means the values are round numbers representative of actual result values which have more digits and some uncertainty.
3. Keywords: D (deuterium, H-2), H (hydrogen), He (helium), He-3, Li (lithium), Li-7, mass fraction, metal, substance, Z (metalliticity).
4. Recall that metals in astro-jargon are elements that are NOT hydrogen and helium and that Z (metalliticity) is the total mass fraction of the metals.
5. The mass fractions are believed to much the same for stars, the interstellar medium (ISM), and the intergalactic medium (IGM) throughout the observable universe and cosmic time. However, metalliticity at the present cosmic time varies wildly from the primordial values given above to of order a few percent. However, the relative abundances of the metals is believed to be approximately constant. Thus, the general stellar composition and cosmic composition are approximately solar composition, except for variations in the total metalliticity.
6. References: Asplund et al. (2009, p. 46, A-2009), Grevesse & Sauval (1998, G-1998), (but see Asplund et al. (2009, p. 46) for values), Table: Solar Composition, Wikipedia: Big Bang: Primordial cosmic composition (which explicitly gives primordial cosmic composition (fiducial values by mass fraction: 0.75 H, 0.25 He-4, 0.001 D, 0.0001 He-3, 10**(-9) Li-7)), Wikipedia: Cosmic composition, Wikipedia: Solar composition.
7. The leading metals in the Solar composition mass fraction are: oxygen (O), carbon (C), iron (Fe), neon (Ne), silicon (Si), nitrogen (N), magnesium (Mg), sulfur (S) (see Table: Solar Composition).
8. The difference between the G-1998 and A-2009 solar metallicity (Z_☉) values is the solar abundance problem. Both the G-1998 and A-2009 values are obtained mainly by modeling the solar atmosphere: the newer value being supposedly an improvement on the older value. However, helioseismology favors G-1998 value, and so suggests there is some systematic error with the A-2009 value (Gough 2019). The solar abundance problem is a significant despite metals being a trace abundance because their large opacity gives them a large effect on solar structure and thus on the modeling of the Sun. Hopefully, a measurement of the neutrino flux from the CNO cycle in the Sun's core will provide circa 2019 a high accuracy/precision value of Z_☉, and lead to a resolution of the solar abundance problem. The measurement will be done by the Borexino Collaboration (2007--). Since the Z_☉ is used as an input in calculating the absolute metallicity of all other stars, obtaining a high accuracy/precision value of Z_☉ is important for all astronomy and in particular cosmichemical evolution.