So the demand destruction is going to be focused very strongly on fuels made with crude oil. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
Very little actually. US plastics production mostly comes from nat gas (cheaper). In China/Japan/Europe you get it more from cracking naphtha.
Just add up the pieces in the US's 20 MMBD. The data is all in the EIA website tables.