I'm implementing support for US week numbers, but there's conflicting
information on the great interweb tubes as to what the standard is.
Some sources say the US Standard is Week 1 is from Jan 1 to the first Saturday
of the year (which may be less than 7 days) then each following week starts
Other sources say Week 1 starts on the first Sunday in the year, with the days
preceeding it being labelled either Week 0 or the last week of the previous
Finally there's some suggestion the US military uses simple week numbering,