Building damage question

When a building is damaged is its production proportioned if above 1. i.e. if you had a tank factory L1 it would take say 2 hours to produce an armoured car. If a L1 tank factory is less than 100% it wont produce at all. However if it was a level 2 tank plant damaged say to 75% does it produce at 1.5 times or only 1 times the production rate (because it is not a whole integer)?