pre_text: NOTE 6. ACCOUNTS RECEIVABLE AND REVENUES Amounts billed and due from our customers are classified as accounts receivables on our consolidated balance sheets and require
  payment on a short-term basis. Invoices are generally issued at the point control transfers and substantially all of our invoices are due
  within 30 days or less, however certain customers have terms of up to 120 days. For substantially all of our contracts, control of the
  ordered product(s) transfers at our location. Periodically, we require payment prior to the point in time we recognize revenue. Amounts
  received from customers prior to revenue recognition on a contract are contract liabilities, are classified as customer prepayments liability on our consolidated balance sheets and are typically applied to an invoice within 30 days of the prepayment. Revenues in 2019 include $0.1 million in unearned revenue as of December 31, 2018, and in 2018 include less than $0.1 million in unearned revenue as of
  January 1, 2018. Our accounts receivable potentially subject us to significant concentrations of credit risk. Revenues and accounts receivable from significant customers (customers with revenue or accounts receivable in excess of 10% of consolidated totals) are stated below as a percent of consolidated totals.
table: Customer
table: A B C D E
table: % of revenue, 2019 11% 9% 16% 3% 2%
table: % of revenue, 2018 17% 14% 1% 4% -%
table: % of accounts receivable, as of December 31, 2019 10% 8% 31% -% 10%
table: % of accounts receivable, as of December 31, 2018 13% -% 16% 14% -%
question: Analyse this data from a financial earnings document. What is the change in the amount of accounts receivable as a percentage of revenue from customer C between 2018 and 2019?