select
cus.tin,
lt.sum_portfolio as portfolio,
case when (sum(lt.sum_portfolio) over())=0 then null
else (round(100*lt.sum_portfolio/sum(lt.sum_portfolio) over(), 2) || '%') end as "%"
from tbl_customer as cus
inner join (select sum(
    case when type = 'loan' then amount
        when type = 'loan_repayment' then -1*amount
        when type = 'interest' then amount
        when type = 'interest_repayment' then -1*amount
    end
) as sum_portfolio,
customer_id
from tbl_loan_transaction
group by customer_id
) lt on (cus.id = lt.customer_id)
where lt.sum_portfolio is not null
group by cus.tin, lt.sum_portfolio
order by lt.sum_portfolio desc;