Given that the war ended in August 2014, one would think that the number of damaged houses would have been pretty much stable shortly afterwards.
The February 2015 report said that 156,000 houses were damaged or destroyed.
The April report said the number was 161,700.
By October, the number of houses damaged in Gaza by August 2014 had gone up to 171,519. (It has remained fairly steady since then.)
Is it possible that the number of damaged houses increased by 10% when there were no bombs falling?
It may be possible that people waited over a year to report legitimate damage on their homes, but that seems very unlikely.
Perhaps some Gazans "damaged" their homes to become eligible to receive cement - which they could then sell to Hamas on the black market.
It is just a theory, but I can't come up with a better one.