12. Peanut butter
Price decline from December 2018 to December 2019: 5%
Peanut butter prices have been falling for five years now, according to an August 2019 report by IBISWorld.
The business and market research firm explains:
“The industry’s overall lackluster performance is mostly a result of operators lowering the price of peanut butter to remain competitive in a concentrated industry. … Despite revenue declines, peanut butter remains a consumer staple and does not experience wild fluctuations in demand, even during periods of economic downturn.”