human
equity in net earnings of affiliated companies equity income from the m-i swaco joint venture in 2010 represents eight months of equity income through the closing of the smith transaction. interest expense interest expense of $298 million in 2011 increased by $91 million compared to 2010 primarily due to the $4.6 billion of long-term debt that schlumberger issued during 2011. interest expense of $207 million in 2010 decreased by $14 million compared to 2009 primarily due to a decline in the weighted average borrowing rates, from 3.9% (3.9%) to 3.2% (3.2%). research & engineering and general & administrative expenses, as a percentage of revenue, were as follows:.
|  | 2011 | 2010 | 2009 |
| --------- | --------- | --------- | --------- |
| Research & engineering | 2.7% | 3.3% | 3.5% |
| General & administrative | 1.1% | 1.1% | 1.1% |
although research & engineering decreased as a percentage of revenue in 2011 as compared to 2010 and in 2010 compared to 2009, it has increased in absolute dollars by $154 million and $117 million, respectively. these increases in absolute dollars were driven in large part by the impact of the smith acquisition. income taxes the schlumberger effective tax rate was 24.4% (24.4%) in 2011, 17.3% (17.3%) in 2010, and 19.6% (19.6%) in 2009. the schlumberger effective tax rate is sensitive to the geographic mix of earnings. when the percentage of pretax earnings generated outside of north america increases, the schlumberger effective tax rate will generally decrease. conversely, when the percentage of pretax earnings generated outside of north america decreases, the schlumberger effective tax rate will generally increase. the effective tax rate for both 2011 and 2010 was impacted by the charges and credits described in note 3 to the consolidated financial statements. excluding the impact of these charges and credits, the effective tax rate in 2011 was 24.0% (24.0%) compared to 20.6% (20.6%) in 2010. this increase in the effective tax rate, excluding the impact of the charges and credits, was primarily attributable to the fact that schlumberger generated a larger proportion of its pretax earnings in north america in 2011 as compared to 2010 as a result of improved market conditions and the effect of a full year 2019s activity from the acquired smith businesses. the effective tax rate for 2009 was also impacted by the charges and credits described in note 3 to the consolidated financial statements, but to a much lesser extent. excluding charges and credits, the effective tax rate in 2010 was 20.6% (20.6%) compared to 19.2% (19.2%) in 2009. this increase is largely attributable to the geographic mix of earnings as well as the inclusion of four months 2019 results from the acquisition of smith, which served to increase the schlumberger effective tax charges and credits schlumberger recorded significant charges and credits in continuing operations during 2011, 2010 and 2009. these charges and credits, which are summarized below, are more fully described in note 3 to the consolidated financial statements. .
Please answer the following questions with expressions if necessary.
what was the change in research & engineering as a percent of revenue from 2010 to 2011?
assistant
subtract(2.7, 3.3)
human
and what was the value of research & engineering as a percent of revenue in 2010?
assistant
3.3
human
how much, then does that change represent in relation to this value, in percentage?
assistant
subtract(2.7, 3.3), divide(#0, 3.3)