According to surveys of O. Donnat "The French cultural practices", attendance at public libraries has increased from 23% in 1989 31% in 1997 and 28% in 2008.
French cultural practices:
http://www.pratiquesculturelles.culture.gouv.fr/doc/enquete97/chap5.pdf
1997 2008 http://tinyurl.com/yzwuefq
Moreover, the average number of books read increased from 23 in 1989 to 21 in 1997, then 16 in 2008.
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All this is somewhat less optimistic than the Credoc which in 2006 announced "library use has doubled since 1989." He had a change of 23% to 43%, university and municipal libraries combined. 
Credoc: http://www.credoc.fr/pdf/4p/193.pdf
