Comparative amounts for certain income statement categories are shown below:

Millions of dollars 2008 2007 2006
Sales and other operating revenues $264,958 $214,091 $204,892

Sales and other operating revenues increased in the comparative periods due mainly to higher prices for crude oil, natural gas and refined products.

Millions of dollars 2008 2007 2006
Income from equity affiliates $5,366 $4,144 $4,255

Income from equity affiliates increased in 2008 from 2007 on improved upstream-related earnings at Tengizchevroil (TCO) due to higher prices for crude oil. Lower income from equity affiliates between 2006 and 2007 was mainly due to a decline in earnings from CPChem, Dynegy (sold in May 2007) and downstream affiliates in the Asia-Pacific area. Partially offsetting these declines were improved results for TCO and income for a full year from Petroboscan, which was converted from an operating service agreement to a joint-stock company in October 2006. Refer to Note 12 for a discussion of Chevron's investments in affiliated companies.

Millions of dollars 2008 2007 2006
Other income $2,681 $2,669 $971

Other income of $2.7 billion in 2008 included gains of approximately $1.3 billion on asset sales. Other income of $2.7 billion in 2007 included net gains of $1.7 billion from asset sales and a loss of $245 million on the early redemption of debt. Interest income was approximately $340 million in 2008 and $600 million in both 2007 and 2006. Foreign currency effects benefited other income by $355 million in 2008 while reducing other income by $352 million and $260 million in 2007 and 2006, respectively.

Millions of dollars 2008 2007 2006
Purchased crude oil and products $171,397 $133,309 $128,151

Crude oil and product purchases in 2008 increased $38.1 billion from 2007 due to higher prices for crude oil, natural gas and refined products. Crude oil and product purchases in 2007 increased more than $5 billion from 2006 due to these same factors.

Millions of dollars 2008 2007 2006
Operating, selling, general and
administrative expenses		 $26,551 $22,858 $19,717

Operating, selling, general and administrative expenses in 2008 increased approximately $3.7 billion from 2007 primarily due to $1.2 billion of higher costs for employee and contract labor; $800 million of increased costs for materials, services and equipment; $700 million of uninsured losses associated with hurricanes in the Gulf of Mexico in 2008; and an increase of about $300 million for environmental remediation activities. Total expenses were about $3.1 billion higher in 2007 than in 2006. Increases were recorded in a number of categories, including $1.5 billion of higher costs for employee and contract labor.

Millions of dollars 2008 2007 2006
Exploration expense $1,169 $1,323 $1,364

Exploration expenses in 2008 declined from 2007 due mainly to lower amounts for well write-offs for operations in the United States. Expenses in 2007 were essentially unchanged from 2006.

Millions of dollars 2008 2007 2006
Depreciation, depletion and amortization $9,528 $8,708 $7,506

Depreciation, depletion and amortization expenses increased in 2008 from 2007 largely due to higher depreciation rates for certain crude oil and natural gas producing fields, reflecting completion of higher-cost development projects and asset-retirement obligations. The increase between 2006 and 2007 reflects an increase in charges related to asset write-downs and higher depreciation rates for certain crude oil and natural gas producing fields worldwide.

Millions of dollars 2008 2007 2006
Taxes other than on income $21,303 $22,266 $20,883

Taxes other than on income decreased between 2007 and 2008 periods mainly due to lower import duties as a result of the effects of the 2007 sales of the company's Benelux refining and marketing businesses and a decline in import volumes in the United Kingdom. Taxes other than on income increased between 2006 and 2007 due to higher import duties in the company's U.K. downstream operations in 2007.

Millions of dollars 2008 2007 2006
Interest and debt expense $- $166 $451

Interest and debt expense decreased significantly in 2008 because all interest-related amounts were being capitalized. Interest and debt expense in 2007 decreased from 2006 primarily due to lower average debt balances and higher amounts of interest capitalized.

Millions of dollars 2008 2007 2006
Income tax expense $19,026 $13,479 $14,838

Effective income tax rates were 44 percent in 2008, 42 percent in 2007 and 46 percent in 2006. Rates were higher between 2007 and 2008 primarily due to a greater proportion of income earned in tax jurisdictions with higher income tax rates. In addition, the 2007 period included a relatively low effective tax rate on the sale of the company’s investment in Dynegy common stock and the sale of downstream assets in Europe. Rates were lower in 2007 compared with 2006 due mainly to the impact of nonrecurring items in 2007 mentioned above and the absence of 2006 charges related to a tax-law change that increased tax rates on upstream operations in the U.K. North Sea and the settlement of a tax claim in Venezuela. Refer also to the discussion of income taxes in Note 16.