BEIJING, June 22 (Xinhua) -- China's courier sector posted steady business expansion in May, official data showed. The country's courier firms delivered about 5.23 billion pieces of parcels last month, up 25.2 percent year on year, according to the State Post Bureau (SPB). Business revenue rose 24.2 percent year-on-year to reach 61.81 billion yuan (about 9.03 billion U.S. dollars). A total of 22.3 billion parcels were delivered during the past five months, raking in about 275.36 billion yuan in business revenue. Southern Chinese city Guangzhou reported the largest number of courier deliveries in May, while Shanghai outperformed others in terms of business revenue, SPB data showed.