SELECT
    ( ( avgWithCriteria - totalAverage ) / ( ( avgWithCriteria + totalAverage ) / 2 ) ) * 100 as percentDifference,
    a.*
FROM
    (SELECT
        AVG( CASE WHEN 'f' not in ( has_free_parking ) THEN price ELSE null END) as avgWithCriteria,
        AVG( CASE WHEN 'f'        in ( has_free_parking ) THEN price ELSE null END) as avgWithoutCriteria,
        AVG( price ) as totalAverage,
        neighbourhood_cleansed
    FROM listings
   WHERE city_name="berlin"
   AND price <= 1000000
   AND price >= -1
   AND reviews_per_month <= 1000000
   AND reviews_per_month >= -1
   AND est_monthly_income <= 1000000
   AND est_monthly_income >= -1
   GROUP BY neighbourhood_cleansed ) a;