Exactly my point. Even we assume that the magazine readers represent 99% of all people , the demand of 85 houses will only grow as the % of (Magazine readers / All people ) reduces!
Hmm, I think you're getting mixed up a bit.
If 85% of House Magazine readers are planning on buying a house soon, but House Magazine readers are only 1% of the population (just an example), then you can't assume that percentage would be evenly distributed to the rest of the country. Obviously people who read a magazine about Houses are more interested in buying or selling a House than the average person, so the results of their survey may be skewed.