abiomed , inc . and subsidiaries notes to consolidated financial statements 2014 ( continued ) evidence of an arrangement exists , ( 2 ) delivery has occurred or services have been rendered , ( 3 ) the seller 2019s price to the buyer is fixed or determinable , and ( 4 ) collectibility is reasonably assured . further , sab 104 requires that both title and the risks and rewards of ownership be transferred to the buyer before revenue can be recognized . in addition to sab 104 , we follow the guidance of eitf 00-21 , revenue arrangements with multiple deliverables . we derive our revenues primarily from product sales , including maintenance service agreements . the great majority of our product revenues are derived from shipments of our ab5000 and bvs 5000 product lines to fulfill customer orders for a specified number of consoles and/or blood pumps for a specified price . we recognize revenues and record costs related to such sales upon product shipment . maintenance and service support contract revenues are recognized ratably over the term of the service contracts based upon the elapsed term of the service contract . government-sponsored research and development contracts and grants generally provide for payment on a cost-plus-fixed-fee basis . revenues from these contracts and grants are recognized as work is performed , provided the government has appropriated sufficient funds for the work . under contracts in which the company elects to spend significantly more on the development project during the term of the contract than the total contract amount , the company prospectively recognizes revenue on such contracts ratably over the term of the contract as it incurs related research and development costs , provided the government has appropriated sufficient funds for the work . ( d ) translation of foreign currencies all assets and liabilities of the company 2019s non-u.s . subsidiaries are translated at year-end exchange rates , and revenues and expenses are translated at average exchange rates for the year in accordance with sfas no . 52 , foreign currency translation . resulting translation adjustments are reflected in the accumulated other comprehensive loss component of shareholders 2019 equity . currency transaction gains and losses are included in the accompanying statement of income and are not material for the three years presented . ( e ) warranties the company routinely accrues for estimated future warranty costs on its product sales at the time of sale . our products are subject to rigorous regulation and quality standards . warranty costs are included in cost of product revenues within the consolidated statements of operations . the following table summarizes the activities in the warranty reserve for the two fiscal years ended march 31 , 2006 ( in thousands ) .

2005: balance at the beginning of the year: 245
accrual for warranties: 198
warranty expense incurred for the year: -212
balance at the end of the year: 231
2006: balance at the beginning of the year: 231
accrual for warranties: 193
warranty expense incurred for the year: -257
balance at the end of the year: 167

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Questions:
what was the balance of warranty reserves at the end of 2006?
what was the balance end the end of 2005?
what is the net difference?
what was the 2005 balance?
what is the net difference over that?

Answers:
167
231
-64
231
-28%