The U.S. Navy, like the other services, has a problem with more and more personnel assigned to take care of dependents (families of sailors) needs. An example of this is the number of naval officers that are in the Medical Service Corps. These are not doctors or dentists, but medical administrators assigned to take care of the medical needs of 500,000 sailors and marines and, more frequently, the 720,000 dependents of the sailors and marines. While the marines have only some 170,000 troops, most of their support functions are provided by the navy. In effect, the Marine Corps is larger than their numbers would suggest. Thus, as a result of the need to supply officers for units providing support services for the marines, only 45 percent of naval officers are designated as unrestricted line officers (qualified to command sailors on board a ship.)