Economic useful life is the duration of time an asset is expected to be productively employed by us, which may be less than its physical life.
Assumptions on the following factors, among others, affect the determination of estimated economic useful life: wear and tear, obsolescence, technical standards, contract life, market demand, competitive position, raw material availability, and geographic location.
The estimated economic useful life of an asset is monitored to determine its appropriateness, especially in light of changed business circumstances.
For example, changes in technology, changes in the estimated future demand for products, or excessive wear and tear may result in a shorter estimated useful life than originally anticipated.
In these cases, we would depreciate the remaining net book value over the new estimated remaining life, thereby increasing depreciation expense per year on a prospective basis.
Likewise, if the estimated useful life is increased, the adjustment to the useful life decreases depreciation expense per year on a prospective basis.
We have numerous long-term customer supply contracts, particularly in the gases on-site business within the Tonnage Gases segment.
These contracts principally have initial contract terms of 15 to 20 years.
There are also long-term customer supply contracts associated with the tonnage gases business within the Electronics and Performance Materials segment.
These contracts principally have initial terms of 10 to 15 years.
Additionally, we have several customer supply contracts within the Equipment and Energy segment with contract terms that are primarily five to 10 years.
The depreciable lives of assets within this segment can be extended to 20 years for certain redeployable assets.
Depreciable lives of the production assets related to long-term contracts are matched to the contract lives.
Extensions to the contract term of supply frequently occur prior to the expiration of the initial term.
As contract terms are extended, the depreciable life of the remaining net book value of the production assets is adjusted to match the new contract term, as long as it does not exceed the physical life of the asset.
The depreciable lives of production facilities within the Merchant Gases segment are principally 15 years.
Customer contracts associated with products produced at these types of facilities typically have a much shorter term.
The depreciable lives of production facilities within the Electronics and Performance Materials segment, where there is not an associated long-term supply agreement, range from 10 to 15 years.
These depreciable lives have been determined based on historical experience combined with judgment on future assumptions such as technological advances, potential obsolescence, competitors’ actions, etc.
Management monitors its assumptions and may potentially need to adjust depreciable life as circumstances change.
A change in the depreciable life by one year for production facilities within the Merchant Gases and Electronics and Performance Materials segments for which there is not an associated long-term customer supply agreement would impact annual depreciation expense as summarized below:
## Table 0 ##
Impairment of Assets Plant and Equipment Plant and equipment held for use is grouped for impairment testing at the lowest level for which there is identifiable cash flows.
Impairment testing of the asset group occurs whenever events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable.
Such circumstances would include a significant decrease in the market value of a long-lived asset grouping, a significant adverse change in the manner in which the asset grouping is being used or in its physical condition, a history of operating or cash flow losses associated with the use of the asset grouping, or changes in the expected useful life of the long-lived assets.
If such circumstances are determined to exist, an estimate of undiscounted future cash flows produced by that asset group is compared to the carrying value to determine whether impairment exists.
If an asset group is determined to be impaired, the loss is measured based on the difference between the asset group’s fair value and its carrying value.
An estimate of the asset group’s fair value is based on the discounted value of its estimated cash flows.
Assets to be disposed of by sale are reported at the lower of carrying amount or fair value less cost to sell.
The assumptions underlying cash flow projections represent management’s best estimates at the time of the impairment review.
Factors that management must estimate include industry and market conditions, sales volume and prices, costs to produce, inflation, etc.
Changes in key assumptions or actual conditions that differ from estimates could result in an impairment charge.
We use reasonable and supportable assumptions when performing
The following table presents net revenues and operating profit data for the Company’s three principal segments for 2012, 2011 and 2010.
## Table 1 ##
U. S.  and Canada U. S.  and Canada segment net revenues for the year ended December 30, 2012 decreased 6% in 2012 compared to 2011 while net revenues for the year ended December 25, 2011 decreased 2% in 2011 compared to 2010.
The impact of currency translation was not material in either period.
In 2012, lower net revenues from boys and preschool products partially offset by higher net revenues from girls and games products contributed to the segment’s decline while lower net revenues from girls and games products partially offset by higher net revenues from boys and preschool products contributed to the segment’s decline in 2011 compared to 2010.
The Company’s expectation in 2012 was that a higher portion of U. S.  and Canada segment net revenues would shift to the second half of the year as part of a strategy to more closely align shipments with consumer demand.
However, the challenging retail environment in the United States during the holiday season resulted in the segment not realizing the level of shipments in the later part of the fourth quarter that had been anticipated which contributed to the overall 6% decline in net revenues in the segment.
In 2012, higher net revenues from MY LITTLE PONY and EASY BAKE products as well as the introduction of FURBY and ONE DIRECTION products contributed to growth in the girls category.
These increases were partially offset by lower net revenues from FURREAL FRIENDS, STRAWBERRY SHORTCAKE, LITTLEST PET SHOP and BABY ALIVE products in 2012.
In 2011, moderately higher net revenues from MY LITTLE PONY and BABY ALIVE products compared to 2010 were more than offset by lower net revenues from FURREAL FRIENDS and LITTLEST PET SHOP products.
In the games category, higher net revenues from MAGIC: THE GATHERING, TWISTER, BATTLESHIP and boys’ action gaming products, primarily STAR WARS and TRANSFORMERS products, in 2012 were partially offset by lower net revenues from other game brands.
Similarly, in 2011, higher net revenues from MAGIC: THE GATHERING products compared to 2010 were more than offset by lower net revenues from board games.
In the boys category, higher sales of MARVEL products, particularly movie-related products related to THE AVENGERS and SPIDER-MAN, in 2012 compared to 2011 were more than offset by lower net revenues from TRANSFORMERS, STAR WARS, BEYBLADE and NERF products.
In 2011, higher net revenues from TRANSFORMERS, particularly movie-related products, compared to 2010 as well as higher sales of BEYBLADE products and the introduction of KRE-O products were partially offset by lower net revenues from NERF and to a lesser extent STAR WARS and TONKA products.
Increased net revenues from PLAYSKOOL HEROES, primarily MARVEL-related, and to a lesser extent higher net revenues from PLAY-DOH products were more than offset by decreased sales of SESAME STREET and TONKA products.
In 2011, higher net revenues from SESAME STREET, TRANSFORMERS and STAR WARS products compared to 2010 were partially offset by lower net revenues from PLAYSKOOL, TONKA and PLAY-DOH products.
PART II Item 5.
Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities Our common stock began trading on the New York Stock Exchange (‘‘NYSE’’) under the symbol ‘‘PFG’’ on October 23, 2001.
Prior to such date, there was no established public trading market for our common stock.
On February 10, 2010, there were 445,236 stockholders of record of our common stock.
The following table presents the high and low prices for our common stock on the NYSE for the periods indicated and the dividends declared per share during such periods.
## Table 2 ##
We declared an annual cash dividend of $0.50 per common share on October 26, 2009, and paid such dividend on December 4, 2009, to stockholders of record on the close of business on November 13, 2009.
We declared an annual cash dividend of $0.45 per common share on October 11, 2008, and paid such dividend on December 5, 2008, to stockholders of record on the close of business on November 14, 2008.
Future dividend decisions will be based on and affected by a number of factors, including our operating results and financial requirements and the impact of regulatory restrictions.
See Item 7.
‘‘Management’s Discussion and Analysis of Financial Condition and Results of Operations — Liquidity and Capital Resources’’ for a discussion of regulatory restrictions on Principal Life’s ability to pay us dividends.
The following table presents the amount of our share purchase activity for the periods indicated: Issuer Purchases of Equity Securities
## Table 3 ##
(1) Reflects the number of shares of common stock utilized to execute certain stock incentive awards in 2009.
(2) During November 2007, our Board of Directors authorized a share repurchase program of up to $500.0 million of our outstanding common stock.
As of December 31, 2009, $250.0 million remained under the November 2007 authorization.
We suspended purchases of our common stock effective October 13, 2008, under the existing share repurchase program.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>Decrease LifeBy 1 Year</td><td>Increase Life By 1 Year</td></tr><tr><td>Merchant Gases</td><td>$32</td><td>$-24</td></tr><tr><td>Electronics and Performance Materials</td><td>$12</td><td>$-11</td></tr></table>
<table><tr><td></td><td> 2012</td><td>% Change</td><td> 2011</td><td>% Change</td><td> 2010</td></tr><tr><td>Net Revenues</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. and Canada</td><td>$2,116,297</td><td>-6%</td><td>$2,253,458</td><td>-2%</td><td>$2,299,547</td></tr><tr><td>International</td><td>$1,782,119</td><td>-4%</td><td>$1,861,901</td><td>19%</td><td>$1,559,927</td></tr><tr><td>Entertainment and Licensing</td><td>$181,430</td><td>12%</td><td>$162,233</td><td>19%</td><td>$136,488</td></tr><tr><td>Operating Profit</td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>U.S. and Canada</td><td>$319,072</td><td>15%</td><td>$278,356</td><td>-20%</td><td>$349,594</td></tr><tr><td>International</td><td>$215,489</td><td>-20%</td><td>$270,578</td><td>29%</td><td>$209,704</td></tr><tr><td>Entertainment and Licensing</td><td>$53,191</td><td>24%</td><td>$42,784</td><td>-1%</td><td>$43,234</td></tr></table>
<table><tr><td> </td><td> High</td><td> Low</td><td> Dividends</td></tr><tr><td> 2009</td><td></td><td></td><td></td></tr><tr><td>First quarter</td><td>$24.80</td><td>$5.41</td><td>—</td></tr><tr><td>Second quarter</td><td>$24.90</td><td>$7.74</td><td>—</td></tr><tr><td>Third quarter</td><td>$30.87</td><td>$16.77</td><td>—</td></tr><tr><td>Fourth quarter</td><td>$30.07</td><td>$22.20</td><td>$0.50</td></tr><tr><td> 2008</td><td></td><td></td><td></td></tr><tr><td>First quarter</td><td>$68.94</td><td>$47.23</td><td>—</td></tr><tr><td>Second quarter</td><td>$59.53</td><td>$41.90</td><td>—</td></tr><tr><td>Third quarter</td><td>$54.28</td><td>$34.80</td><td>—</td></tr><tr><td>Fourth quarter</td><td>$45.49</td><td>$8.78</td><td>$0.45</td></tr></table>
<table><tr><td> Period</td><td> Total Number of Shares (or Units) Purchased (1)</td><td> Average Price Paid per Share (or Unit)</td><td> Total Number of Shares (or Units) Purchased as Part of Publicly Announced Plans or Programs</td><td> Maximum Number (or Approximate Dollar Value) of Shares (or Units) that May Yet Be Purchased Under the Plans or Programs (in millions) (2)</td></tr><tr><td>January 1, 2009 — January 31, 2009</td><td> 1,697</td><td>$22.13</td><td> —</td><td>$250.0</td></tr><tr><td>February 1, 2009 — February 28, 2009</td><td> 136,948</td><td>$16.83</td><td> —</td><td>$250.0</td></tr><tr><td>March 1, 2009 — March 31, 2009</td><td> 67,054</td><td>$9.56</td><td> —</td><td>$250.0</td></tr><tr><td>April 1, 2009 — April 30, 2009</td><td> 20,532</td><td>$8.63</td><td> —</td><td>$250.0</td></tr><tr><td>May 1, 2009 — May 31, 2009</td><td> 851</td><td>$18.86</td><td> —</td><td>$250.0</td></tr><tr><td>June 1, 2009 — June 30, 2009</td><td> 27,189</td><td>$18.94</td><td> —</td><td>$250.0</td></tr><tr><td>July 1, 2009 — July 31, 2009</td><td> 16,482</td><td>$18.84</td><td> —</td><td>$250.0</td></tr><tr><td>August 1, 2009 — August 31, 2009</td><td> 649</td><td>$25.09</td><td> —</td><td>$250.0</td></tr><tr><td>September 1, 2009 — September 30, 2009</td><td> —</td><td>$—</td><td> —</td><td>$250.0</td></tr><tr><td>October 1, 2009 — October 31, 2009</td><td> 288</td><td>$27.28</td><td> —</td><td>$250.0</td></tr><tr><td>November 1, 2009 — November 30, 2009</td><td> 800</td><td>$28.43</td><td> —</td><td>$250.0</td></tr><tr><td>December 1, 2009 — December 31, 2009</td><td> 546</td><td>$25.00</td><td> —</td><td>$250.0</td></tr><tr><td>Total</td><td> 273,036</td><td></td><td> —</td><td></td></tr></table>

Question: In which section the sum of Total Number of Shares has the highest value?
Answer: February 1, 2009 — February 28, 2009