Dear reader! I also interested in the same matter, which is number and tonnage of the ships \ cargo vessels, sunk and damaged by British HM Subs. Now preparation of the detailed table in progress. The problem is coming with neutral vessels, which were indicated as sunk or lost during WW1 without any cause. For example, a lot of Sweden cargo vessels were sunk in Baltic sea. Approximately 1/3 out of the total lost were sunk by German U-Boats, another 1/3 because of mines, several number sunk by Russian submarines and warships, but the rest of total number should be identified in more exact manner. Some data contains in the Sweden historical websites> but for the time being I am not ready to publish the above mentioned stat because of a lack of significant details. My email = sfm@mail.ru - do not hesitate to request if you are interested in the same matter.