SELECT
    AGE as 'AGE'
    ,CASE
    WHEN GENDER_CODE = '20' THEN 'MALE'
    WHEN GENDER_CODE = '30' THEN 'FEMALE'
  END as 'GENDER'
    ,CASE
    WHEN CATEGORY_CODE = '10' THEN AVG(AVERAGE_VALUE)
  END as 'H_AVG'
FROM
    SCHOOL_HEALTH
WHERE
    SURVEY_YEAR = 2019
GROUP BY
    AGE
    ,GENDER
ORDER BY
    AGE desc
    ,GENDER_CODE desc
;