pre_text: Concentration of Credit Risk and Significant Customers Financial instruments that potentially subject us to concentrations of credit risk consist of cash, cash equivalents, marketable securities and accounts receivable. Our cash, cash equivalents and marketable securities are held and invested in high-credit quality financial instruments by recognized financial institutions and are subject to minimum credit risk. Our accounts receivable are unsecured and represent amounts due to us based on contractual obligations of our customers. We mitigate credit risk in respect to accounts receivable by performing periodic credit evaluations based on a number of factors, including past transaction experience, evaluation of credit history and review of the invoicing terms of the contract. We generally do not require our customers to provide collateral to support accounts receivable. Significant customers, including distribution channel partners and direct customers, are those which represent 10% or more of our total revenue for each period presented or our gross accounts receivable balance as of each respective balance sheet date. Revenues from our significant customers as a percentage of our total revenue are as follows *represents less than 10% of total revenue As of December 31, 2019, two customers accounted for 17% and 12% of our total gross accounts receivable.
  As of December 31, 2018, two customers accounted for 16% and 12% of our total gross accounts receivable
table: Years Ended December 31,
table: 2019 2018 2017
table: Customer A (a distribution channel partner) * 14% *
table: Customer B (a distribution channel partner) 12% 10% *
table: Customer C (a distribution channel partner) 14% * *
question: Analyse this data from a financial earnings document. What is the total proportion from Customer B and C of the company's gross accounts receivable  in 2019?