SELECT ROUND(AVG(TOTAL_VALUE)) AS SA_MEDIAN
FROM (
    SELECT TOTAL_VALUE,
           ROW_NUMBER() OVER (ORDER BY TOTAL_VALUE) AS rn,
           COUNT(*) OVER () AS cnt
    FROM CONVENIENCE
    WHERE SURVEY_YEAR = 2019
      AND KIND_CODE = '100'
) AS sub
WHERE rn = (cnt + 1) / 2 OR rn = (cnt + 2) / 2;