Despite the presence of a strong Microsoft Office 2008 offering, Apple’s own iWork office suite continues to grow, with a 50% surge in sales in 2009.

The NPD Group has announced that Apple’s answer to Microsoft’s popular Office suite, iWork ’09, sold 50% more units in the first 11 months on the market (from January to November of this year) than its predecessor, iWork ’08, sold in the same timeframe, according to AppleInsider.

By comparison, the iLife ’09 bundle included with all new Macs -- comprised of iPhoto, iMovie, Garage Band, iWeb and iDVD -- sold roughly the same number of units as the previous iLife ’08 during the same 11 months.

For the first time, Apple also offered iWork this year in a $169 box set ($229 family pack) which also included iLife ’09 and Mac OS X 10.6 Snow Leopard. However, NPD’s numbers do not include those bundle sales.

“These have been, I think, pretty successful products for them (Apple), generating a lot of pretty decent average selling prices and decent revenue numbers,” NPD vice president of industry analysis Steven Baker explained to AppleInsider.

iWork ’09 includes the Pages word processor, Numbers spreadsheet software and Keynote presentation software in one bundle for $79, or in a $99 family pack that can be installed on up to five computers. Baker notes that the single-user version of iWork has quietly been a big seller for Apple.

Mac OS X 10.6 Snow Leopard was also a big hit for Apple this year, particularly with its $29 retail price. The lower price strategy appears to have paid off, with record numbers for early adoption -- twice as strong as the previous version, 10.5 Leopard, and four times better than 10.4 Tiger.

“They’ve been pretty successful, obviously, with being more aggressive in pricing,” Baker said. “Certainly that was a big reason why Snow Leopard got such a big uptick right off the bat.”