select
round(avg(total_value)) as SA_MEDIAN
from(select total_value
      from convenience
      where survey_year = 2019 and kind_code ='100'
      order by 1
      limit 2 - (select count(*) from convenience where survey_year = 2019 and kind_code ='100') % 2    -- odd 1, even 2
      offset (select (count(*) - 1) / 2
              from convenience
              where survey_year = 2019 and kind_code ='100'))