research , development and related expenses : research , development and related expenses ( r&d ) as a percent of net sales decreased 1.0 percentage point in 2007 when compared to 2006 , as expenses incurred in 2006 in the company 2019s now-divested r&d-intensive pharmaceuticals business did not repeat in 2007 . non-pharmaceutical ongoing r&d expenses , after adjusting for the following items , were up approximately 11% ( 11 % ) in dollars , as the company continued to aggressively invest in future technologies and growth opportunities . 2006 spending included a $ 95 million in-process research and development charge ( discussed in note 2 ) and $ 75 million in restructuring actions ( note 4 ) , which increased 2006 r&d as a percent of sales by 0.7 percentage points . in dollars , r&d spending decreased $ 154 million when comparing 2007 to 2006 , with the change in restructuring and other items year-on-year decreasing r&d by $ 174 million , 2006 pharmaceutical sg&a spending decreasing $ 120 million and other r&d spending increasing $ 140 million , or approximately 11% ( 11 % ) in dollars , reflecting 3m 2019s continuing commitment to fund future growth for the company . r&d increased as a percent of sales by 0.6 of a percentage point , or $ 248 million , when comparing 2006 to 2005 . the 2006 spending included a $ 95 million in-process research and development charge ( discussed in note 2 ) and $ 75 million in restructuring actions ( note 4 ) . other spending increased approximately $ 78 million , representing an increase of approximately 6% ( 6 % ) compared with 2005 . gain on sale of businesses : in january 2007 , 3m completed the sale of its global branded pharmaceuticals business in europe to meda ab . 3m received proceeds of $ 817 million for this transaction and recognized , net of assets sold , a pre-tax gain of $ 781 million in 2007 ( recorded in the health care segment ) . in june 2007 , 3m completed the sale of its opticom priority control systems and canoga traffic detection businesses to torquest partners inc. , a toronto-based investment firm . 3m received proceeds of $ 80 million for this transaction and recognized , net of assets sold , transaction and other costs , a pre-tax gain of $ 68 million ( recorded in the display and graphics segment ) in 2007 . in december 2006 , 3m completed the sale of its global branded pharmaceuticals businesses in the united states , canada , and latin america region and the asia pacific region , including australia and south africa . 3m received proceeds of $ 1.209 billion for these transactions and recognized a pre-tax gain on sale of $ 1.074 billion in 2006 ( recorded in the health care segment ) . for more detail , refer to note 2 . operating income : 3m uses operating income as one of its primary business segment performance measurement tools . operating income margins over the past several years have been in excess of 22% ( 22 % ) , helped by solid sales growth and an ongoing strong commitment to maintaining operational discipline throughout 3m 2019s global operations . operating income margins of 25.3% ( 25.3 % ) in 2007 were positively impacted by 2.8 percentage points ( $ 681 million ) from the gain on sale of businesses and real estate , net of environmental liabilities , restructuring and other exit activities . operating income margins of 24.8% ( 24.8 % ) for 2006 were positively impacted by 2.2 percentage points ( $ 523 million ) from the gain on sale of portions of the pharmaceuticals business , net of restructuring and other actions . adjusting for the preceding items , operating income margins in 2007 were similar to 2006 . interest expense and income: .
in 2007 what was the ratio of the interest expense to the interest income
interest expense : interest expense increased year-on-year in both 2007 and 2006 , primarily due to higher average debt balances and higher interest rates . interest income : interest income increased in 2007 due to higher average cash , cash equivalent and marketable securities balances and higher interest rates . interest income was lower in 2006 , with lower average cash , cash equivalent and marketable securities balances partially offset by higher interest rates. .