All statistical facts refer to the past. The United States Census of April 1970 counted 203 million of us, but no one knew this until the following November, and the details of the count were published over the course of years. The census differs only in degree from stock market prices, which are hours old before they appear in the daily press. There are no exceptions—not even statistics of intentions—to the rule that all data are to some degree obsolete by the time they reach us.