R&D expense increased 36% during 2011 compared to 2010, it declined slightly as a percentage of net sales, due to the 66% year-over-year growth in the Company’s net sales during 2011.
R&D expense increased 34% or $449 million to $1.8 billion in 2010 compared to 2009.
This increase was due primarily to an increase in headcount and related expenses in the current year to support expanded R&D activities.
Also contributing to this increase in R&D expense in 2010 was the capitalization in 2009 of software development costs of $71 million related to Mac OS X Snow Leopard.
Although total R&D expense increased 34% during 2010, it declined as a percentage of net sales given the 52% year-over-year increase in net sales in 2010.
The Company continues to believe that focused investments in R&D are critical to its future growth and competitive position in the marketplace and are directly related to timely development of new and enhanced products that are central to the Company’s core business strategy.
As such, the Company expects to make further investments in R&D to remain competitive.
Selling, General and Administrative Expense (“SG&A”) SG&A expense increased $2.1 billion or 38% to $7.6 billion during 2011 compared to 2010.
This increase was due primarily to the Company’s continued expansion of its Retail segment, increased headcount and related costs, higher spending on professional services and marketing and advertising programs, and increased variable costs associated with the overall growth of the Company’s net sales.
SG&A expense increased $1.4 billion or 33% to $5.5 billion in 2010 compared to 2009.
This increase was due primarily to the Company’s continued expansion of its Retail segment, higher spending on marketing and advertising programs, increased share-based compensation expenses and variable costs associated with the overall growth of the Company’s net sales.
Other Income and Expense Other income and expense for the three years ended September 24, 2011, are as follows (in millions):
## Table 0 ##
Total other income and expense increased $260 million or 168% to $415 million during 2011 compared to $155 million and $326 million in 2010 and 2009, respectively.
The year-over-year increase in other income and expense during 2011 was due primarily to higher interest income and net realized gains on sales of marketable securities.
The overall decrease in other income and expense in 2010 compared to 2009 was attributable to the significant declines in interest rates on a year-over-year basis, partially offset by the Company’s higher cash, cash equivalents and marketable securities balances.
Additionally the Company incurred higher premium expenses on its foreign exchange option contracts, which further reduced the total other income and expense.
The weighted average interest rate earned by the Company on its cash, cash equivalents and marketable securities was 0.77%, 0.75% and 1.43% during 2011, 2010 and 2009, respectively.
During 2011, 2010 and 2009, the Company had no debt outstanding and accordingly did not incur any related interest expense.
Provision for Income Taxes The Company’s effective tax rates were approximately 24.2%, 24.4% and 31.8% for 2011, 2010 and 2009, respectively.
The Company’s effective rates for these periods differ from the statutory federal income tax rate of
(4) Includes securities related to the Build America Bonds program.
(5) Excluded from the table above are securities held outside the general account in other entities and operations.
For additional information regarding investments held outside the general account, see “—Invested Assets of Other Entities and Operations” below.
Also excluded from the table above are fixed maturity securities classified as trading.
See “—Trading Account Assets Supporting Insurance Liabilities” and “—Other Trading Account Assets” for additional information.
The increase in net unrealized gains from December 31, 2015 to December 31, 2016, was primarily due to a net increase in fair value driven by a decrease in interest rates in Japan and credit spread tightening.
Asset-Backed Securities The following tables set forth the amortized cost and fair value of our asset-backed securities attributable to PFI excluding the Closed Block division, by credit quality, as of the dates indicated: Asset-Backed Securities at Amortized Cost
## Table 1 ##
(1) While there is no market standard definition for securities collateralized by sub-prime mortgages, we define sub-prime mortgages as residential mortgages that are originated to weaker-quality obligors as indicated by weaker credit scores, as well as mortgages with higher loan-to-value ratios or limited documentation.
(2) All of the $398 million of education loans included above carry a Department of Education guaranty as of December 31, 2016.
(3) Includes asset-backed securities collateralized by bond obligations, aircraft, equipment leases, franchises and timeshares.
(4) Excluded from the table above are asset-backed securities held outside the general account in other entities and operations.
Also excluded from the table above are asset-backed securities classified as trading.
Asset-Backed Securities at Fair Value
## Table 2 ##
(1) While there is no market standard definition for securities collateralized by sub-prime mortgages, we define sub-prime mortgages as residential mortgages that are originated to weaker-quality obligors as indicated by weaker credit scores, as well as mortgages with higher loan-to-value ratios or limited documentation.
(2) All of the $407 million of education loans included above carry a Department of Education guaranty as of December 31, 2016.
(3) Includes asset-backed securities collateralized by bond obligations, aircraft, equipment leases, franchises and timeshares.
(4) Excluded from the table above are asset-backed securities held outside the general account in other entities and operations.
Also excluded from the table above are asset-backed securities classified as trading.
The tables above provide ratings as assigned by nationally recognized rating agencies as of December 31, 2016, including Standard & Poor’s, Moody’s and Fitch.
In making our investment decisions, rather than relying solely on the rating agencies’ evaluations, we assign internal ratings to our asset-backed securities based upon our dedicated asset-backed securities unit’s independent evaluation of the underlying collateral and securitization structure, including any guarantees from monoline bond insurers.
Asset Management operations The principal sources of liquidity for our fee-based asset management businesses include asset management fees and commercial mortgage origination and servicing fees.
The principal uses of liquidity include general and administrative expenses and distributions of dividends and returns of capital to Prudential Financial.
The primary liquidity risks for our fee-based asset management businesses relate to their profitability, which is impacted by market conditions and our investment management performance.
We believe the cash flows from our fee-based asset management businesses are adequate to satisfy the current liquidity requirements of these operations, as well as requirements that could arise under reasonably foreseeable stress scenarios, which are monitored through the use of internal measures.
The principal sources of liquidity for our strategic investments held in our asset management businesses are cash flows from investments, the ability to liquidate investments, and available borrowing lines from internal sources, including Prudential Financial and Prudential Funding, LLC (“Prudential Funding”), a wholly-owned subsidiary of Prudential Insurance.
The primary liquidity risks include the inability to sell assets in a timely manner, declines in the value of assets and credit defaults.
There were no material changes to the liquidity position of our asset management operations during 2016.
Alternative Sources of Liquidity In addition to the sources of liquidity discussed above, and asset-based financing as discussed below, Prudential Financial and certain subsidiaries have access to other sources of liquidity, including membership in the Federal Home Loan Banks, commercial paper programs, and a put option agreement.
The Company also maintains syndicated, unsecured committed credit facilities as an alternative source of liquidity.
In September 2016, PHJ, a wholly-owned subsidiary of Prudential Financial, entered into a ￥100 billion three-year syndicated, unsecured committed credit facility.
See Note 14 to our Consolidated Financial Statements for more information on these sources of liquidity.
Asset-based Financing We conduct asset-based or secured financing within our insurance and other subsidiaries, including transactions such as securities lending, repurchase agreements and mortgage dollar rolls, to earn spread income, to borrow funds, or to facilitate trading activity.
These programs are primarily driven by portfolio holdings of securities that are lendable based on counterparty demand for these securities in the marketplace.
The collateral received in connection with these programs is primarily used to purchase securities in the short-term spread portfolios of our insurance entities.
Investments held in the short-term spread portfolios include cash and cash equivalents, short-term investments, mortgage loans and fixed maturities, including mortgage-and asset-backed securities, with a weighted average life at time of purchase by the short-term portfolios of four years or less.
Floating rate assets comprise the majority of our short-term spread portfolio.
These short-term portfolios are subject to specific investment policy statements, which among other things, do not allow for significant asset/liability interest rate duration mismatch.
The following table sets forth our liabilities under asset-based or secured financing programs as of the dates indicated.

Tables referenced above, in order (Table 0 first):
<table><tr><td></td><td>2011</td><td>2010</td><td>2009</td></tr><tr><td>Interest and dividend income</td><td>$519</td><td>$311</td><td>$407</td></tr><tr><td>Other expense, net</td><td>-104</td><td>-156</td><td>-81</td></tr><tr><td>Total other income and expense</td><td>$415</td><td>$155</td><td>$326</td></tr></table>
<table><tr><td></td><td colspan="6">December 31, 2016</td><td></td></tr><tr><td></td><td colspan="5">Lowest Rating Agency Rating</td><td></td><td></td></tr><tr><td></td><td>AAA</td><td>AA</td><td>A</td><td>BBB</td><td>BB andbelow</td><td>TotalAmortizedCost</td><td>TotalDecember 31,2015</td></tr><tr><td></td><td colspan="7">(in millions)</td></tr><tr><td>Collateralized by sub-prime mortgages-1</td><td>$0</td><td>$0</td><td>$18</td><td>$36</td><td>$352</td><td>$406</td><td>$1,141</td></tr><tr><td>Collateralized loan obligations</td><td>6,178</td><td>18</td><td>0</td><td>0</td><td>0</td><td>6,196</td><td>4,280</td></tr><tr><td>Collateralized by education loans-2</td><td>28</td><td>370</td><td>0</td><td>0</td><td>0</td><td>398</td><td>392</td></tr><tr><td>Collateralized by credit cards</td><td>116</td><td>0</td><td>0</td><td>0</td><td>0</td><td>116</td><td>201</td></tr><tr><td>Collateralized by auto loans</td><td>818</td><td>0</td><td>0</td><td>0</td><td>0</td><td>818</td><td>518</td></tr><tr><td>Other asset-backed securities-3</td><td>7</td><td>75</td><td>38</td><td>22</td><td>106</td><td>248</td><td>341</td></tr><tr><td>Total asset-backed securities-4</td><td>$7,147</td><td>$463</td><td>$56</td><td>$58</td><td>$458</td><td>$8,182</td><td>$6,873</td></tr></table>
<table><tr><td></td><td colspan="6">December 31, 2016</td><td></td></tr><tr><td></td><td colspan="5">Lowest Rating Agency Rating</td><td></td><td></td></tr><tr><td></td><td>AAA</td><td>AA</td><td>A</td><td>BBB</td><td>BB andbelow</td><td>TotalFair Value</td><td>TotalDecember 31,2015</td></tr><tr><td></td><td colspan="7">(in millions)</td></tr><tr><td>Collateralized by sub-prime mortgages-1</td><td>$0</td><td>$0</td><td>$19</td><td>$36</td><td>$432</td><td>$487</td><td>$1,189</td></tr><tr><td>Collateralized loan obligations</td><td>6,231</td><td>18</td><td>0</td><td>0</td><td>0</td><td>6,249</td><td>4,317</td></tr><tr><td>Collateralized by education loans-2</td><td>28</td><td>379</td><td>0</td><td>0</td><td>0</td><td>407</td><td>395</td></tr><tr><td>Collateralized by credit cards</td><td>119</td><td>0</td><td>0</td><td>0</td><td>0</td><td>119</td><td>206</td></tr><tr><td>Collateralized by auto loans</td><td>816</td><td>0</td><td>0</td><td>0</td><td>0</td><td>816</td><td>516</td></tr><tr><td>Other asset-backed securities-3</td><td>6</td><td>76</td><td>43</td><td>22</td><td>124</td><td>271</td><td>376</td></tr><tr><td>Total asset-backed securities-4</td><td>$7,200</td><td>$473</td><td>$62</td><td>$58</td><td>$556</td><td>$8,349</td><td>$6,999</td></tr></table>

Question: What is the difference between the greatest Collateralized loan obligations in AAA and AA? (in million)
Answer: 6213
Reasoning program: subtract(6231,18)