How many times can enter China a Multiple entries,12 mo/90 days each stay,enter before Dec.8/2012 ?

I have a multiple entries,12 months,90 days each stay visa,enter before Dec 8/2012.
I used first entry July 1- Aug 26/2012.How many times I still can enter China and can I enter the
next year 2013 and when ? Is my visa still valid in 2013 ?How many entries a Multiple entry visa has ?
Thank you.