The FBAR report calculates your highest FIAT value for each Exchange during the selected calendar year. Use those values to file your FBAR report.
Who Must File FBAR?
A US citizen that has a financial interest in or signature authority over foreign financial accounts must file an FBAR, if the aggregate value of the foreign financial accounts exceeds $10,000 at any time during the calendar year. More details on the IRS website
Update: June 2019
CoinTracking Blog post: US-based crypto traders: here's what to do if you forgot to file your FBAR
Please make sure that all your transactions, especially deposits and withdrawals of FIAT currencies, are listed in your CoinTracking account.