Don't have a breakdown of merchant sinkings only in front of me here at work, but...
After the war, the Joint Army-Navy Assessment Committee (JANAC) attempted to reconcile all Japanese shipping losses over 500 tons with the cause. While certainly not 100% accurate, the JANAC figures should be considered in the ballpark. JANAC credited the US submarines with sinking 1,314 ships for 5.3 million tons. Included in these sinkings were one battleship, eight aircraft carriers, three heavy cruisers and eight light cruisers. This represented 55 percent of Japan's maritime losses. By comparison, German submarines in WW2 sank 2,882 ships for 14.4 million tons (it should be noted the Germans were at war for 2+ years longer than the US)
52 US submarines were lost to all causes, taking down with them 375 officers and 3,131 enlisted men (out of 16,000 who made war patrols), for a loss rate of 22 percent, the highest loss rate for any US service branch during WW2, but lowest loss rate among submarine branches among the major combatants. By comparison, the Germans lost 781 boats, the Japanese 130 and the Italians 85.
Source: Blair's Silent Victory
Big thanks to whomever it was that showed me how to paste into this forum
