the average time from the moment the goods to be used for obtaining the compensating products enter the factory until the moment they leave the factory. This period shall be determined from the ratio at cost price of the value of the average stock of goods necessary for obtaining the compensating products to the annual turnover., tiettynä aikana toteutuneen liikevaihdon tai käyttömäärän suhde varastossa olevaan määrään,kun molempien laskemiseen on käytetty samaa hintaperustetta