with total_values as (
    select
        total_value,
        (row_number() over (order by total_value) - 1) as i
    from
        convenience
    where
        survey_year = 2019 and
        kind_code = '100'
    order by
        total_value
)
select
    round(avg(total_value)) as SA_MEDIAN
from
    total_values
where
    i = ((select count(*) from total_values) - 1) / 2 or
    i = (select count(*) from total_values) / 2
;