instruction: For how many patients with coronary atherosclerosis of native coronary artery was the ethnic origin unknown/unspecified?
response: SELECT COUNT(DISTINCT demographic.subject_id) FROM demographic INNER JOIN diagnoses ON demographic.hadm_id = diagnoses.hadm_id WHERE demographic.ethnicity = "UNKNOWN/NOT SPECIFIED" AND diagnoses.long_title = "Coronary atherosclerosis of native coronary artery"