Copywriter and marketing consultant Jerry Jones says that no matter what cross-section of the population you analyze, they will sort themselves into 5%, 10%, and 85%.
For example, 5% of your customers are doing great and can buy anything you offer. About 10% will respond and be able to buy. And 85% will say they cannot buy, either because they think they can’t afford it or are not motivated enough to get the result you offer.
Source: The Direct Mail Profit Insider, 5/13, p. 1.