select avg(TOTAL_VALUE)
from (
    select TOTAL_VALUE
    from CONVENIENCE
    where SURVEY_YEAR = 2019
    and KIND_CODE = 100
    order by TOTAL_VALUE asc
    
    limit ( 2 - 
            
            (
            select (count(*) % 2)
            from CONVENIENCE
            where SURVEY_YEAR = 2019
            and KIND_CODE = 100
            )
        )
    
    offset (
        select (count(*) -1) /2
        from CONVENIENCE
        where SURVEY_YEAR = 2019
        and KIND_CODE = 100
    )
    
)