ru_translate | en->ru, need help

Procter & Gamble has ended the fourth quarter of its fiscal year with net sales of $ 18.9 bn, an increase of 5 per cent compared with the previous year. Overall sales for fiscal 2010 grew by 3 per cent to $ 78.9 bn. Growth was also recorded in the snacks and pet care segments, where net sales increased by 1 per cent to $ 3.1 bn for the current financial year. Unit volume declined 2 per cent, driven by lower shipments in snacks. As a result of the higher net sales, increased margins and a lower tax rate, net earnings in the snacks and pet care segment also rose to $ 326 mio.

Что такое unit volume в данном контексте?

Заранее большое спасибо!