After a month-to-month dip in April, pending sales of existing homes jumped back to a two-year high in May, according to the National Association of Realtors' latest Pending Home Sales Index released today. The index, which represents contracts signed but not yet closed, rose a seasonally adjusted 5.9 percent from April to May, to 101.1 -- the same index level as in March and the highest index level since April 2010, when the deadline for a federal homebuyer tax credit program was fast approaching. The index was 111.3 then. An index score of 100 is equal to the average level of sales contract activity in 2001, a year in which home sales fell in a range that's considered "normal" for the current U.S. population. Contracts signed in May typically close one or two months later....