"imposed since" is correct and can be used in written English.
The phrase is usually used in the context of a rule, regulation, or other requirement having been imposed at some point in the past and still being in effect. For example: "Stricter safety regulations have been imposed since the accident."
The U.N. resolution approved last week is the fourth set of sanctions imposed since 2006.
A 24-hour curfew has been imposed since the beginning of December.
It follows £250m in cuts imposed since David Cameron became prime minister.
It comes on top of $5.7 million in fines the agency has imposed since 2003.
Israel says medical supplies can reach Gaza despite the blockade imposed since 2006 and tightened in 2007.
The sentence is the longest the court has imposed since it began dealing with war crimes in 2000.
Egypt experienced an unprecedented surge in 2008 in the political involvement of its citizens, whose activities flouted limitations imposed since 1981 by the state of emergency.
Those energy surcharges that have been imposed since last winter by top hotel chains are beginning to disappear after prompting widespread complaints and lawsuits.
A ban has been imposed since last December across the European Union on selling the constituent parts of the lethal injection to US prisons.
Diplomats point out that these are the first sanctions imposed since last June's disputed presidential elections, which brought mass protests against the government of President Mahmoud Ahmadinejad and discredited the supreme leader, Ayatollah Ali Khamenei.
Working out final agreements on issues ranging from border demarcation to items stolen from the Kuwaiti national archives will be a priority for the next Iraqi government, said Mr. Zebari, so that Iraq can free itself of all Security Council restrictions imposed since 1990.
