et le chiffre des emplois non-agricoles, supérieur aux prévisions,

on ne peut certainement pas dire qu'un taux de chômage de 8,3% (voir chiffres du bureau of Labor Statistics ci-dessous" soit "plus bas que tout". Ca reste un taux de chômage très élevé pour les Etats-Unis, mais il est en baisse,, ce qi explique sans doute l'utilisation de "knockout".

"knockout : Informal . a person or thing overwhelmingly attractive, appealing, or successful. "
http://dictionary.reference.com/browse/knockout?s=b

"Total nonfarm payroll employment rose by 243,000 in January, and the
unemployment rate decreased to 8.3 percent, the U.S. Bureau of Labor
Statistics reported today. Job growth was widespread in the private
sector, with large employment gains in professional and business
services, leisure and hospitality, and manufacturing. Government
employment changed little over the month.

-----------------------------------------------------------------
| |
| Changes to The Employment Situation Data |
| |
|Establishment survey data have been revised as a result of the |
|annual benchmarking process and the updating of seasonal |
|adjustment factors. Also, household survey data for January 2012 |
|reflect updated population estimates. See the notes at the end of|
|the news release for more information about these changes. |
| |
-----------------------------------------------------------------

Household Survey Data

The unemployment rate declined by 0.2 percentage point in January to
8.3 percent; the rate has fallen by 0.8 point since August. (See table
A-1.) The number of unemployed persons declined to 12.8 million in
January. (See the note and tables B and C for information about annual
population adjustments to the household survey estimates.)"
http://www.bls.gov/news.release/empsit.nr0.htm

--------------------------------------------------
Note added at 1 hr (2012-03-05 10:31:26 GMT)
--------------------------------------------------

"


United States Unemployment Rate
The unemployment rate in the United States fell to 8.3 percent in January of 2012, the lowest since February 2009. From 1948 until 2010 the United States' Unemployment Rate averaged 5.70 percent reaching an historical high of 10.80 percent in November of 1982 and a record low of 2.50 percent in May of 1953. The labour force is defined as the number of people employed plus the number unemployed but seeking work. The nonlabour force includes those who are not looking for work, those who are institutionalised and those serving in the military. This page includes: United States Unemployment Rate chart, historical data and news."
http://www.tradingeconomics.com/united-states/unemployment-r...