Which French accented characters are most frequently used?

I don’t speak French, but I’m writing a little program to help people type in French easily.

I need to know the order in decreasing frequency of each set of letters below. For example, for the “e” group, is the order è, é, ê, ë.

à
â
ä

è
é
ê
ë

î
ï

ô
œ

ù
û
ü

ÿ

Ç
ç
€

Thanks a lot guys! French looks really hard. :P