AMERICAN TOWER CORPORATION AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) to purchase 3,924 and 911 shares, respectively.
In October 2005, in connection with the exercise by Mr.  Gearon of his right to require the Company to purchase his interest in ATC South America, these options vested in full and were exercised.
Upon exercise of these options, the holders received 4,428 shares of ATC South America, net of 1,596 shares retained by the Company to satisfy employee tax withholding obligations.
The 1,596 shares retained by the Company were treated as a repurchase of a minority interest in accordance with SFAS No.141.
As a result, the Company recorded a purchase price allocation adjustment of $5.6 million as an increase to intangible assets and a corresponding increase in minority interest as of the date of acquisition.
The holders had the right to require the Company to purchase their shares of ATC South America at their then fair market value six months and one day following their issuance.
In April 2006, this repurchase right was exercised, and the Company paid these holders an aggregate of $18.9 million in cash, which was the fair market value of their interests on the date of exercise of their repurchase right, as determined by the Company’s Board of Directors with the assistance of an independent financial advisor.12.
IMPAIRMENTS, NET LOSS ON SALE OF LONG-LIVED ASSETS, RESTRUCTURING AND MERGER RELATED EXPENSE The significant components reflected in impairments, net loss on sale of long-lived assets, restructuring and merger related expense in the accompanying consolidated statements of operations include the following: Impairments and Net Loss on Sale of Long-Lived Assets—During the years ended December 31, 2006, 2005 and 2004, the Company recorded impairments and net loss on sale of long-lived assets (primarily related to its rental and management segment) of $3.0 million, $19.1 million and $22.3 million, respectively.  ?
Non-Core Asset Impairment Charges—During the years ended December 31, 2006 and 2005 respectively, the Company recorded net losses associated with the sales of certain non-core towers and other assets, as well as impairment charges to write-down certain assets to net realizable value after an indicator of potential impairment had been identified.
As a result, the Company recorded net losses and impairments of approximately $2.0 million, $16.8 million and $17.7 million for the years ended December 31, 2006, 2005 and 2004, respectively.
The net loss for the year ended December 31, 2006 is comprised net losses from asset sales and other impairments of $7.0 million, offset by gains from asset sales of $5.1 million.  ?
Construction-In-Progress Impairment Charges—For the years ended December 31, 2006, 2005 and 2004, the Company wrote-off approximately $1.0 million, $2.3 million and $4.6 million, respectively, of construction-in-progress costs, primarily associated with sites that it no longer planned to build.
Restructuring Expense—The following table displays activity with respect to the accrued restructuring liability for the years ended December 31, 2004, 2005 and 2006 (in thousands):
## Table 0 ##
The accrued restructuring liability is reflected in accounts payable and accrued expenses in the accompanying consolidated balance sheets as of December 31, 2005.
During the year ended December 31, 2006, the Company
AMERICAN TOWER CORPORATION AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) The following table summarizes the Company’s option activity for the periods presented:
## Table 1 ##
The following table sets forth information regarding options outstanding at December 31, 2006:
## Table 2 ##
Voluntary Option Exchanges—In February 2004, the Company issued to eligible employees 1,064,353 options with an exercise price of $11.19 per share.
These options were issued in connection with a voluntary option exchange program entered into by the Company in August 2003, pursuant to which the Company accepted for surrender and cancelled options to purchase a total of 1,881,981 shares of its Class A common stock having an exercise price of $10.25 or greater.
The program, which was offered to both full and part-time employees,
AMERICAN TOWER CORPORATION AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) 16.
DISCONTINUED OPERATIONS In connection with the Company’s focus on its core tower business, the Company has sold several non-core businesses.
In accordance with SFAS No.144, the Company classified the results of these businesses as discontinued operations in the accompanying consolidated statements of operations.
The following table presents summary results of the discontinued operations for the years ended December 31, (in thousands):
## Table 3 ##
The following businesses have been reflected as discontinued operations in the accompanying consolidated statements of operations for the applicable periods presented.
Impairment charges and gains (losses) are presented net of taxes.
Tower Construction Services Unit—In November 2004, the Company consummated the sale of its tower construction services unit (previously included in the Company’s network development services segment), including $3.9 million of inventory and $5.2 million of net property and equipment.
Total consideration was approximately $9.1 million, including $6.8 million of cash proceeds, subject to adjustment, and the buyer’s assumption of $2.3 million of capital lease obligations.
Pursuant to this transaction, the Company recorded a net loss on disposal of approximately $1.7 million, which is reflected in loss from discontinued operations, net, in the accompanying consolidated statement of operations for the year ended December 31, 2004.
Kline, Iron & Steel—In March 2004, the Company sold substantially all the assets of its steel fabrication and tall tower construction service subsidiary, Kline, Iron & Steel (previously included in the Company’s network development services segment), for approximately $4.0 million.
The Company had previously recorded charges to impair Kline’s net assets and reduce their carrying value to the estimated proceeds expected upon disposal.
Verestar—In December 2003, Verestar filed for protection under Chapter 11 of the federal bankruptcy laws.
Under generally accepted accounting principles, consolidation is generally required for investments of more than 50% of the outstanding voting stock of an investee, except when control is not held by the majority owner.
Under these rules, legal reorganization or bankruptcy represent conditions which can preclude consolidation in instances where control rests with the bankruptcy court, rather than the majority owner.
Accordingly, due to the bankruptcy filing, the Company ceased to consolidate Verestar’s financial results beginning December 22, 2003.
As described in note 9, the Company has incurred costs in connection with its involvement in the bankruptcy proceedings of Verestar of $0.9 million, $1.3 million and $0.1 million, which are reflected within the net loss on disposal of discontinued operations in the accompanying consolidated statements of operations for the years ended December 31, 2006, 2005 and 2004, respectively.
The net loss on disposal for the year ended December 31, 2004 also includes a $1.3 million net gain related to certain contractual obligations that were settled for less than the Company’s original estimate.
(See note 9. )
AMERICAN TOWER CORPORATION AND SUBSIDIARIES NOTES TO CONSOLIDATED FINANCIAL STATEMENTS—(Continued) periods, employees purchased 53,210, 50,119 and 85,750 shares, respectively, at weighted average prices per share of $24.98, $15.32 and $10.64, respectively.
The fair value of the ESPP offerings is estimated on the offering period commencement date using a Black-Scholes pricing model with the expense recognized over the expected life, which is the six month offering period over which employees accumulate payroll deductions to purchase the Company’s Class A common stock.
The fair value for the ESPP shares purchased during the June 2006, December 2005, June 2005 and December 2004 offering periods was $7.29, $6.37, $4.13 and $6.12, respectively.
At December 31, 2006, 3,944,288 shares remain reserved for future issuance under the plan.
Key assumptions used to apply this pricing model are as follows:

<table><tr><td></td><td>Liability as of January 1, 2004</td><td>2004 Expense</td><td>2004 Cash Payments</td><td>Liability as of December 31, 2004</td><td>2005 Expense</td><td>2005 Cash Payments</td><td>Liability as of December 31, 2005</td><td>2006 Expense</td><td>2006 Cash Payments</td><td>Liability as of December 31, 2006</td></tr><tr><td>Employee separations</td><td>$2,239</td><td>$823</td><td>$-2,397</td><td>$665</td><td>$84</td><td>$-448</td><td>$301</td><td>$-267</td><td>$-34</td><td>$0</td></tr><tr><td>Lease terminations and other facility closing costs</td><td>1,450</td><td>-131</td><td>-888</td><td>431</td><td>12</td><td>-325</td><td>118</td><td>-10</td><td>-108</td><td>0</td></tr><tr><td>Total</td><td>$3,689</td><td>$692</td><td>$-3,285</td><td>$1,096</td><td>$96</td><td>$-773</td><td>$419</td><td>$-277</td><td>$-142</td><td>$0</td></tr></table>
<table><tr><td></td><td>Options</td><td> Weighted Average Exercise Price </td><td> Weighted Average Contractual Term (Years) </td><td> Aggregate Intrinsic Value (in millions)</td></tr><tr><td>Outstanding as of January 1, 2004</td><td>18,534,608</td><td>$10.14</td><td></td><td></td></tr><tr><td>Granted</td><td>5,288,099</td><td>11.25</td><td></td><td></td></tr><tr><td>Exercised</td><td>-6,249,324</td><td>6.41</td><td></td><td></td></tr><tr><td>Cancelled</td><td>-2,283,064</td><td>13.36</td><td></td><td></td></tr><tr><td>Outstanding as of December 31, 2004</td><td>15,290,319</td><td>$11.55</td><td></td><td></td></tr><tr><td>Granted</td><td>7,105,650</td><td>19.74</td><td></td><td></td></tr><tr><td>Options assumed in merger with SpectraSite, Inc.</td><td>9,878,295</td><td>5.54</td><td></td><td></td></tr><tr><td>Exercised</td><td>-11,106,693</td><td>5.70</td><td></td><td></td></tr><tr><td>Cancelled</td><td>-764,069</td><td>16.45</td><td></td><td></td></tr><tr><td>Outstanding as of December 31, 2005</td><td>20,403,502</td><td>$14.48</td><td></td><td></td></tr><tr><td>Granted</td><td>4,806,231</td><td>31.69</td><td></td><td></td></tr><tr><td>Exercised</td><td>-3,884,812</td><td>10.26</td><td></td><td></td></tr><tr><td>Cancelled</td><td>-889,327</td><td>19.48</td><td></td><td></td></tr><tr><td>Outstanding as of December 31, 2006</td><td>20,435,594</td><td>$19.67</td><td>6.84</td><td>$362.5</td></tr><tr><td>Exercisable as of December 31, 2004</td><td>8,121,719</td><td>$14.34</td><td></td><td></td></tr><tr><td>Exercisable as of December 31, 2005</td><td>9,416,743</td><td>$13.03</td><td></td><td></td></tr><tr><td>Exercisable as of December 31, 2006</td><td>9,640,338</td><td>$15.14</td><td>4.95</td><td>$216.1</td></tr><tr><td>Vested or expected to vest as of December 31, 2006</td><td>19,714,818</td><td>$19.46</td><td>6.77</td><td>$354.0</td></tr></table>
<table><tr><td colspan="4"> Options Outstanding </td><td colspan="2"> Options Exercisable </td></tr><tr><td> Outstanding Number of Options </td><td> Range of Exercise Price Per Share </td><td> Weighted Average Exercise Price Per Share </td><td> Weighted Average Remaining Life (Years) </td><td> Options Exercisable </td><td> Weighted Average Exercise Price Per Share </td></tr><tr><td>1,007,570</td><td>$0.75 —$ 3.66</td><td>$3.42</td><td>5.48</td><td>1,007,570</td><td>$3.42</td></tr><tr><td>1,584,064</td><td>3.84 — 10.00</td><td>6.39</td><td>4.44</td><td>1,577,160</td><td>6.38</td></tr><tr><td>3,013,971</td><td>10.50 — 12.11</td><td>11.15</td><td>6.04</td><td>2,392,971</td><td>11.21</td></tr><tr><td>3,492,554</td><td>12.29 — 18.15</td><td>15.78</td><td>6.99</td><td>1,336,914</td><td>15.12</td></tr><tr><td>2,232,725</td><td>18.16 — 18.60</td><td>18.60</td><td>8.15</td><td>306,463</td><td>18.59</td></tr><tr><td>2,804,145</td><td>18.67 — 22.43</td><td>22.02</td><td>6.43</td><td>1,364,995</td><td>21.60</td></tr><tr><td>1,504,700</td><td>22.55 — 31.06</td><td>27.17</td><td>3.59</td><td>1,391,225</td><td>27.46</td></tr><tr><td>4,795,865</td><td>31.50 — 53.62</td><td>32.42</td><td>8.97</td><td>263,040</td><td>45.64</td></tr><tr><td>20,435,594</td><td>$0.75 —$53.62</td><td>$19.67</td><td>6.84</td><td>9,640,338</td><td>$15.14</td></tr></table>
<table><tr><td></td><td>2006</td><td>2005</td><td>2004</td></tr><tr><td>Revenue</td><td></td><td></td><td>$71,993</td></tr><tr><td>Income (loss) from discontinued operations</td><td></td><td>$34</td><td>-11,894</td></tr><tr><td>Income tax (provision) benefit on income (loss) from discontinued operations</td><td></td><td>-12</td><td>4,110</td></tr><tr><td>Net loss on disposal of discontinued operations, net of tax benefit of $444, $1,042 and $337, respectively</td><td>$-854</td><td>-1,935</td><td>-625</td></tr><tr><td>Loss from discontinued operations, net</td><td>$-854</td><td>$-1,913</td><td>$-8,409</td></tr></table>

Question: What's the difference of Options' Outstanding as of December 31 between 2004 and 2005?
Answer: 5113183