SELECT
ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN
FROM (
  SELECT *,
    ROW_NUMBER() OVER (
      PARTITION BY SURVEY_YEAR, KIND_CODE
      ORDER BY TOTAL_VALUE
    ) AS ROWNUM,
    COUNT(1) OVER(PARTITION BY SURVEY_YEAR, KIND_CODE) AS CNT
 FROM CONVENIENCE
 WHERE SURVEY_YEAR = 2019
 AND KIND_CODE = '100'
) AS WORK
WHERE
  ROWNUM BETWEEN CNT * 1.0 / 2 AND CNT * 1.0 / 2 + 1
;