Yep. They alternate decades with the 'Airships are returning for cargo' groups.

About the same frequency the US starts a major war or oil prices skyrocket for someone else's war. 20-ish years ago was the Iraq 2 war. 20-ish years before that was Iraq 1. Now it's the unholy combination of Ukraine beating Russia's refineries and US/Israel striking Iran.

And the higher oil prices go, the more people are interested in saving oil.