The 10 most common disease chapter were: diseases of the circulatory system; endocrine, nutritional and metabolic diseases; diseases of the digestive system; diseases of the respiratory system; diseases of the genitourinary system; diseases of the musculoskeletal system and connective tissue; certain infectious and parasitic diseases; diseases of the ear and mastoid process; symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified; neoplasms.