(In thousands) | 2013 | 2012 | ||||||
Balance at beginning of period | $ | 345,993 | $ | 279,876 | ||||
Deferred revenue recognized upon shipment to distributors | 5,870,096 | 5,517,540 | ||||||
Deferred costs of sales recognized upon shipments to distributors | (269,969 | ) | (238,256 | ) | ||||
Revenue recognized upon sell-through to end customers | (1,055,137 | ) | (1,023,465 | ) | ||||
Costs of sales recognized upon sell-through to end customers | 260,326 | 237,703 | ||||||
Earned distributor price concessions (1) | (4,575,430 | ) | (4,345,473 | ) | ||||
Returns | (88,058 | ) | (82,577 | ) | ||||
(Decrease)/ increase in other deferred revenue | (75 | ) | 645 | |||||
Balance at end of period | $ | 487,746 | $ | 345,993 | ||||
(1) | Average aggregate price concessions typically range from 70% to 85% of our list price on an annual basis, depending upon the composition of our sales, volumes, and factors associated with the timing of shipments to distributors. |