Translate the following English sentence to French:
"The reason for this high percentage is that we do not want to take the risk of sending Finnish wagons to Russia, since experience shows that they are so very rarely returned."
Si cette proportion est aussi élevée, c' est que l' on n' ose pas envoyer des wagons finlandais en Russie. L' expérience montre en effet qu' ils en reviennent rarement.