SELECT
    AVG(TOTAL_VALUE) AS SA_MEDIAN
FROM
(
    SELECT
        TOTAL_VALUE
    FROM
        CONVENIENCE
    WHERE
        SURVEY_YEAR = 2019
    AND KIND_CODE = '100'
    ORDER BY
        TOTAL_VALUE
    LIMIT
        2 - (SELECT COUNT(*) FROM CONVENIENCE) % 2
    OFFSET
        (SELECT (COUNT(*) - 1) / 2 FROM CONVENIENCE)
)