More than 60 percent of the world general cargo trade moved by sea is carried in containers. On trades between highly industrialized countries the percentage approaches more than 90 percent (of the containerizable cargo). This is a remarkable market penetration for a technology that dates only from the mid 1950s, when the first converted ship carrying 58 containers made its initial voyage between New York and Houston. Since then there has been a continual increase in both number and average size of containerships