*  Percentages may not total 100 because of rounding. Covid-19 denotes coronavirus disease 2019.
†  The Defense Enrollment Eligibility Reporting System was used to identify race and ethnic group for all crew members.
‡  Augmented crew reside on the ship only at certain times when a ship is under way and provide specialized capability such as air squadrons, submarine groups, destroyer squadrons, and helicopter maritime strike squadrons.
§  Crew members in the departments of reactor, engineering, supply, weapons and in the combat support division tend to work in more confined spaces than those in the air and deck departments. Crew members in the air and deck departments tend to work in a combination of open-air and confined conditions. Medical personnel work in confined spaces but wear personal protective equipment when caring for crew members.
¶  Underweight was defined as a body-mass index (BMI, the weight in kilograms divided by the square of the height in meters) of less than 18.5; normal or healthy weight, 18.5 to 24.9; overweight, 25.0 to 29.9; and obese, 30 or higher.
‖  Conditions were identified from October 1, 2017, through March 1, 2020, with the use of the following data sources: Theater Medical Data Store, Comprehensive Ambulatory/Professional Encounter Record, Standard Inpatient Data Record, Armed Forces Health Longitudinal Technology Application Clinical Data Repository, Military Health System (MHS) GENESIS, TRICARE Encounter Data, and Periodic Health Assessment.