Personal-computer shipments plummeted in every region of the world in the first quarter as buyers opted for smartphones and tablet computers and Microsoft’s newest operating system met with weak demand.

Global PC unit shipments fell 14 percent in the first quarter — the worst such decline on record — to 76.3 million, a bigger drop than the 7.7 percent decline Interactive Data Corp. had forecast, the market researcher said in a statement this week. The slump was the steepest since IDC began tracking shipments in 1994.

Every PC maker except China’s Lenovo Group experienced declines as businesses chose to install Microsoft’s Windows 7 operating system on employees’ computers instead of the newer Windows 8.