I wonder how the raw material prices for whiskey are factored into retail prices. Presumably the rye was cheaper when the whiskey currently on the shelves was distilled. In any event, I suspect the price increases in recent years reflect a combination of increased costs and increased demand.
I didn't mean to imply that it was a single-year spike in price. Rye was selling for between $2.50 and $3.50 a bushel for well over a decade until 2007 when it jumped to $5 and then went over $6 2008-2009. After dropping to the $5+ range for a couple of years it's now nearing $8. So the distiller's raw materials costs have been substantially higher for the last 5 years. They're finally at a point where they need to pass it on.