with base as (
select
    ROW_NUMBER() over(order by total_value)as rn
    ,TOTAL_VALUE
from
    CONVENIENCE
where
    SURVEY_YEAR =2019
    and KIND_CODE=100
)
select 
    AVG(TOTAL_VALUE)
from
    base
where
    rn between cast((select count(*) from base) as real)/2 and cast((select count(*) from base) as real)/2+1