Naturalisation-90 days of being outside of Belgium rule

Hello,

I remember reading somewhere that if you want to apply for naturalisation there will be a limit of 90 days/year the person can spend outside Belgium.
Does anyone know if the rule applies for the year/years before asking for citizenship or for all years until the day they decide to aprove/reject the application?
So far in the 3 years before i sent my application (May 2012) i left Belgium only for 2 weeks but in 2013 i'm planning an extended trip around Europe and i'd like to know if i can go for more than 90 days and if this is going to influence their decision.
Thank you for helping!