In 2010, the Dugan Co. had net credit sales of $750,000. On January 1, 2010, Allowance for Doubtful Accounts had a credit balance of $16,000. During 2010, $30,000 of uncollectible accounts receivable were written off. Past experience indicates that the allowance should be 10% of the balance in receivables (percentage of receivable basis). If the accounts receivable balance at December 31 was $200,000, what is the required adjustment to the Allowance for Doubtful Accounts at December 31, 2010?