Author: Stephen Bourget
MDL-48953 choice: Improve chart labels
http://git.moodle.org/gw?p=moodle.git;a=commit;h=8520046ad2aaa82143b1eed552776761aedb67a8
http://github.com/moodle/moodle/commit/8520046ad2aaa82143b1eed552776761aedb67a8
+ 2.9 en [numberofuser,mod_choice]
+ 2.9 en [numberofuserinpercentage,mod_choice]