Mitt Romney’s Oldenburg mare, Rafalca, is competing in London for Olympic dressage. Stephen Colbert has declared “competitive horse prancing” his Sport of the Summer, pointedly mocking the presumptive Republican presidential nominee for looking like a 1 percent aristocrat. After all, though Rafalca’s price is undisclosed, when the Romneys bought the horse in 2006, dressage prospects of her caliber cost as much as, if not more than, an average American home. Her annual overhead of more than $77,000 is double that of the average American family’s. No wonder the elite equestriennes gracing this month’s Town & Country are all billionaire princesses. Even at sub-Olympian levels, the animals are expensive.