OPEC’s share in global oil production has structurally declined from ~48% in the 1970s to ~37% projected in 2025, indicating rising dominance of non-OPEC supply. The drop is driven by growth in non-OPEC production, particularly from shale producers in the US. 

Despite its declining share, OPEC continues to retain significant influence due to its large low-cost reserves and coordinated supply management approach. 

OPEC’s role as a swing producer allows it to stabilise or disrupt global oil prices through coordinated production adjustments.