In the following tables you will find

I = Total/(Signal + Background) - 1   [%]

estimated with HTO, where Total = Signal + Interference + Background 
for gg --> ZZ. Therefore, you can take

    (Signal + Background)_your 

and get

     Interference_your

Format is

          bin            I[%]      - [%]          + [%]

     X GeV   X+2 GeV     I in [%]  - Delta I [%]  + Delta I [%]