(Telecompaper) Worldwide tablet shipments totaled 45.1 million units in the second quarter, up 59.6 percent from a year earlier, but down 9.7 percent from the first quarter of this year, according to estimates from IDC. The sequential slowdown was due to no new iPad, with Apple shipping a less-than-expected 14.6 million units in the quarter, down from 19.5 million in Q1. Apple's market share fell to 32.4 percent from 60.3 percent a year ago. Samsung's shipments also slowed, to 8.1 million from 8.6 million in the first three months of the year, giving it 18.0 percent of the market. Asus shipped 2.0 million tablets in Q2, versus 2.6 million in Q1, giving it a 4.5 percent market share. Lenovo passed a million tablets for the first time, shipping in total 1.5 million in Q2, giving it a market share of 3.3 percent. Acer followed with 1.4 million tablets or 3.1 percent of the market. Android was the leading operating system in the quarter, accounting for 62.6 percent of tablets shipped, followed by Apple's iOS with 32.5 percent and Windows with 4.5 percent.