Hi Lily
The consensus is to use 1.14 (unless advised by your tax office to be lower) or on the other hand, if your income is paid direct to your bank in euro, total that up and use that figure or the best of all 3 
From the Latest Topics Of Interest thread (May 2020 Newsletter.pdf):
The exchange rate for 2019 is 1.14 (that is the average of last year). You can get another rate from
your local tax office, use theirs if it is lower than 1.14! Note that when you ask the official Paris tax
office they tell you to use the rate from the “banque de France” on the day you got paid! Or use
the average of the year.