Over the past five years, the market for contemporary art has ballooned. Whether the reason is supply or shifting taste (or, more likely, a combination of both), we live in a world where you can buy an entire Old Master paintings sale at Sotheby’s for less than the cost of one Jeff Koons balloon dog. Of course, there are outliers: Exceptional objects in categories as unsexy as carpets can still fetch eye-popping sums. And price is not always equivalent to cultural value. Major 20th-century works by African-American and women artists, for example, rarely surpass lesser works by their white, male contemporaries. On the heels of the record-shattering postwar- and contemporary-art auctions in New York last month, can you guess which works sold (over the last five years) for the highest price?