Here is everything you ever wanted to know—even things you didn’t know enough to know that you wanted to know—about the back to school season, compiled by our friendly Census Bureau [1], the Washington Post reports. Back-to-School Shopping: $7.4 billion. The amount of money spent at family clothing stores in August 2010. Only in November and December were sales significantly higher. Similarly, sales at bookstores in August 2010 totaled $2.2 billion, an amount approached in 2010 only by sales in January…