Nearly 10 percent fewer tablets of all brands shipped in the second quarter compared to the first, with Apple's iPad line showing the biggest decline -- a 25 percent slide, IDC said today.iPad shipments totaled just 14.6 million in the quarter, down from 19.6 million in the previous quarter. That decline was attributed to the fact that Apple did not offer any iPad updates this spring. New iPads launched before the second quarter in years past have traditionally helped both Apple and its competitors, IDC noted.