The order backlog held by South Korea's top three shipbuilders has dropped by some 26 trillion won, or 22 billion U.S. dollars, in just the past two years. 

According to data compiled by the Hana Institute of Finance, the combined order backlog by the three firms amounted to 96 billion dollars as of the end of the first quarter, down 22 billion dollars, or 18-point-six percent, compared to the end of 2013.

Hyundai Heavy Industries saw the steepest fall of 27-point-three percent. Samsung Heavy Industries saw its order backlog drop 20 percent and Daewoo Shipbuilding and Marine Engineering nine-point-four percent in the past two years. 

Daewoo holds the largest remaining order backlog worth 36-point-eight billion dollars followed by Samsung with 30 billion and Hyundai Heavy with 29 billion dollars. 

The shipbuilding industry, once a cash cow for the domestic economy, has been reeling from a global slump and faces major structural adjustments.