select
    100.00 * sum(
        case
            when p_type like 'PROMO%' then l_extendedprice * (1 - l_discount)
            else 0
        end
    ) / sum(l_extendedprice * (1 - l_discount)) as promo_revenue
from
    lineitem,
    part
where
    l_partkey = p_partkey
    and l_shipdate >= '1995-09-01'
    and l_shipdate < '1995-10-01'
