Improvement of PVC materials for cable over the years

[shlim]

Hi there,

I am looking for any references comparing the quality of PVC-insulated cable made (say) 40-45 years ago vs today.

Is there any improvement(s) in terms of materials composition, or the quality in general, for PVC-insulated cable, made 45 years ago versus the same type of cable made today. Can the improvement(s), if any, be expressed in a quantitative manner?

Thank you.