I used the following letter distribution:
E 115024205 A 67563628 I 62672992 S 61882785 N 60728196 R 57656209 T 56267109 O 47724400 L 47171247 U 42698875 D 34914685 C 30219574 M 24894034 P 23647179 É 18451937 G 11684140 B 10817171 V 10590858 H 10583562 F 10579192 Q 6140307 Y 4351953 X 3588990 J 3276064 È 2969466 À 2966029 K 2747547 W 1653435 Z 1433913
But I'm no expert in french. Is there a better approach?