Before shale took off oil to gas prices averaged 8 to 1 – close to their energy equivalence ratio.
Since 2013 this ratio has averaged 20 to 1.
Outside of North America the ratio is 3 to 1.
“In other words, US gas is priced at an energy-equivalent discount of 56% to world oil and a 77% discount to world gas. In our 35 years investing in global energy markets, we have never seen such a wide disparity.“
Source (including arguments on why it might revert).
