with
result2015 as (
    select * from popu_transition where survey_year = 2015
),
result2020 as (
    select * from popu_transition where survey_year = 2020
),
result as (
    select result2015.pf_code, round(result2015.total_amt*100.0/result2020.total_amt) as ratio from result2015 left outer join result2020
)
select pf_code, ratio from result where ratio > 100 order by ratio desc, pf_code asc;