In general, barring some mostly unpredictable "shock" (like your workforce was destroyed in the plague or something), there is no such thing and it's the kind of thing economists should make fun of and do make fun of in other contexts... but weirdly not this one and I have no idea why (add appropriate sarcastic glaring emoji here).
Supply and demand, baby. Pay your workers more. We're mostly not talking about rocket surgeons. Pay them more, pay to train them.
