It seems as though the vessels that most commonly experience problems are the most commonly present vessels. I don't think that the data allows us to make any conclusions about the relative safety
of diffrent types of boaters.
Oh no! I spoke too soon! Table 24 gives the data by vessel type the OP is right! The guys in the open motorboats are at the far ....far higher risk. Some how this does not surprise me. Those that go out and zip about in a small power boats with alcohol and little knowledge abound!