You in fact shouldn't know this as the EIA reports that 3,239,699 barrels of petroleum products were consumed in august of this year alone for electrical generation in the US (source https://www.eia.gov/totalenergy/data/browser/index.php?tbl=T... )
https://www.eia.gov/tools/faqs/faq.php?id=427&t=3
While your number seems like a lot, it's really just a drop in the bucket. The US consumes close to 8 billion barrels of oil annually. I was, however, surprised that it was still as high as 0.5%.