As expected, Apple reported the first year-over-year quarterly decline in revenue in more than a decade, as sales of $50.56 billion fell below analysts’ lowered expectations. Sales were down in every region except Japan, with China and the rest of Asia declining more than the US (-10%) and Europe (-5%). But in the segment that has the most relevance for the book business, and the area where they are directly competitive with Amazon and Google, the “services” line item that includes the iTunes stores, revenue still grew. Sales of $5.99 billion were up 20 percent from $5 billion a year ago. […]