Roberts Company produces a single product. This year, the company's net operation income under absorption costing was $2,000 lower than under variable costing. The company sold 9,000 units during the year, and its variable costs were $8 per unit, of which $2 was variable selling and administrative expense. If production cost was $10 per unit under absorption costing, then how many units did the company produce during the year? (The company produced the same number of units last year)