It would be better if you used the IRS yearly average exchange rate if you do not know the dates of the losses and the losses occurred at various times during the calendar year (and yes the statement is sufficient as a receipt of your losses).
The Internal Revenue Service has no official
exchange rate. In general, use the exchange rate prevailing (i.e., the spot
rate) when you received the income. Please refer to the following IRS links for
more information about Foreign
Currency and Currency Exchange Rates and Yearly
Average Currency Exchange Rates
