Question: After which world event, did retail establishments in the U.S. began to pursue a high-volume, low-profit-margin strategy in a type of store that sells products at prices that are lower than the typical market value and for example sells Scotsmac, an alcoholic drink consisting of a blend of wine and whisky flavouring, in 700ml bottles?
Sentence (from "Scotsmac"): Scotsmac has a strength of 15%.
Relevant evidence: No