Hazard Company began 2021 with a credit balance of $116,000 in the refund liability account. Sales and cash collections from customers during the year were $1,750,000 and $1,410,000, respectively. During 2021, customers returned merchandise for credit of $67,000 to their accounts. The balance in the refund liability account at the end of 2021 was $136,500. What percent of sales in 2021 does Hazard estimate to be returned?