context: The success of the 1981 Irish hunger strike in mobilising support and winning elections led to what was referred to by Danny Morrison (writer) as, "the Armalite and ballot box strategy" with more time and resources devoted to political activity. The perceived stalemate along with British governments hints of a compromise and secret approaches in the early 1990s led republican leaders increasingly to look for a political agreement to end the conflict, with a broadening dissociation of Sinn Féin from the IRA. Following negotiations with the Social Democratic and Labour Party (SDLP) and secret talks with British civil servants, the IRA ultimately called a ceasefire in 1994 on the understanding that Sinn Féin would be included in political talks for a settlement. When the British government then demanded the disarmament of the IRA before it allowed Sinn Féin into multiparty talks, the organisation called off its ceasefire in February 1996. The renewed bombings caused severe economic damage, with the 1996 Manchester bombing and the Docklands bombing causing approximately £800 million in combined damage. After the ceasefire was reinstated in July 1997, Sinn Féin was admitted into all-party talks, which produced the Good Friday Agreement of 1998. The IRAs armed campaign, primarily in Northern Ireland but also in England and mainland Europe, caused the deaths of approximately 1,800 people. The dead included around 1,100 members of the British security forces, and about 630 civilians. The IRA itself lost 275–300 members, of an estimated 10,000 total over the 30-year period. Between 1970 and 2005, the IRA had detonated 19,000 improvised explosive devices (IEDs) in the United Kingdom, an average of one every 17 hours for three and a half decades, arguably making it "the biggest terrorist bombing campaign in history".
question: How many, on average, were improvised explosive devices detonated per week?
answer: 10