l have no idea how the count works, but since your usage is based on how many MB you download l do not really see it as important. Probably it is based on some average size for a download, which might not actually have anything to do with how many actual comics you downloaded, or what the average size of a comic on the site actually is. Only Serj would have an idea and he is usually busy.
From looking at your stats, which show 310 downloads l would say you are using some sort of download manager. The site will count it as a full download everytime your program connects, using a download manager which downloads multiple pieces of the file at the same time is not recommended. You download one file at a time, via the usual method, or you make sure your program is not making multiple connections for the same download.