The Government Accountability Office published a report (pdf) on the U.S. military logistics for operating in Afghanistan. I have written earlier here on logistics in Afghanistan. The report offers some new or updated numbers which I quote below.

The report also partly explains why the operations in Afghanistan are so expensive. Goods take a long time to reach Afghanistan, a lot gets lost or pilfered or, due to organization chaos, never reaches its customers. The DoD systems involved are not compatible to each other, data is lacking, a lot of paperwork is required and the Afghan and Pakistani bureaucracy make any custom processing a long endeavor.

Some quotes:

Overall, there are about 17 major logistics bases and more than 300 outposts in Afghanistan.
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For surface shipments of sustainment items, DOD did not once achieve its goal of delivering 85 percent of shipments within 97 days of being ordered.
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85 percent of delivered shipments arrived within 165 days.
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Sustainment items delivered to supply warehouses at major logistics bases are either transported to or picked up by the customer who ordered the item. This additional delivery time is not measured against the time-definite delivery standards, which are set only for delivery to a major logistics base.
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In June 2011, U.S. Central Command set a goal that 75 percent of cargo shipped to Afghanistan be transported along the Northern Distribution Network

From a table in the paper we can gather that in 2010 some 15,000 international shipments for military units moving into or out of Afghanistan were made plus some 74,000 shipments of sustainment materials, i.e. construction materials, food, fuel, spare parts etc.

42 percent of unit surface shipments and 19 percent of sustainment surface shipments with required delivery dates in 2008 through 2010 did not have a documented delivery date in the database.
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The ability to maintain visibility using RFID tags throughout theater is inconsistent, even if a cargo truck passes an RFID interrogator. Officials stated that RFID tags lose battery power while in transit, and the batteries are sometimes stolen out of the tags. For example, in October 2010, a DOD check of RFID tags at the Hairaton [Usbekistan/Afghanistan] border crossing found that 80 percent of RFID tags had batteries stolen out of them
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[A]n official at a supply yard in Afghanistan stated that individual cargo items are frequently not documented on RFID tags.
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[A]pproximately 40 percent of the RFID tags on cargo bound for one base in theater had incorrect or incomplete data “burned” onto them
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[A]n official stated a contractor truck took two weeks to bring supplies for his task force to Bagram from Kabul [(that's 25 miles distance!)], in part because the truck kept getting turned away at the gate to the base.
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Officials in Kandahar stated that a convoy of contractor trucks languished for weeks in the staging lot because no one talked to the customer receiving the cargo, and the customer was unaware the trucks were at the entry control point.
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The customs paperwork requires many signatures from specific individuals and transfers among various locations in the Foreign Affairs and Finance customs offices.
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A DOD official in Afghanistan stated that clearing customs paperwork for cargo export takes approximately 38 days, but may take as long as 55 days.
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According to DOD officials, customs and border officials operate on their own time frames to process paperwork and clear cargo, and DOD’s influence and control over customs clearance processing in Pakistan and Afghanistan is limited.
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According to DOD officials, approximately 0.8 percent of all cargo items have been pilfered since 2007 while in transit. … DOD’s process for collecting information on pilferage and damage of cargo is not capturing all incidents.
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Officials from one unit stated they believe that approximately 10 percent of containers processed through Kandahar have been pilfered, but the reported pilferage rate is much lower.
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[O]ne task force official in Afghanistan stated that approximately 7 percent of the brigade’s containers that were transported through Pakistan arrived empty or nearly empty of cargo.

As these are mostly official numbers we can assume that the real numbers, on pilfering and other issues, are worse. Units in Afghanistan are usually there for one year and shorter for Marines. With a half a year delay between ordering and delivery of spare parts and other materials, many of those will only arrive, if at all, when the unit has already left again. This will at any time leave a high rate of vehicles and other technical equipment not operable. It may partly explain how, despite the surge of soldiers, military progress on the ground is quite limited.