Function weeknummer (iYear, iMonth,  iDay)
		 dim thursdayofweek
		 dim firstthursdayofyear
		 dim MyDay
		 dim dayofWeek
		 dim thursdaysyear

		 MyDay = DateSerial(iYear, iMonth, iDay)

		 dayofWeek		 = Weekday(MyDay)
		 if dayofWeek = 1 then
		 		  thursdayofweek = dateadd("d", -3 , MyDay)
		 else
		 		  thursdayofweek = dateadd("d",(5 - dayofWeek), MyDay)
		 end if
		 thursdaysyear = Year( thursdayofweek )

		 firstthursdayofyear = first_thursday_of_year (thursdaysyear)

		 weeknummer = (datediff("ww", firstthursdayofyear ,thursdayofweek) + 1)
end		 Function

function first_thursday_of_year (iYear)
		 dim first_jan
		 dim dayofWeek

		 first_jan = DateSerial(iYear, 1, 1)
		 dayofWeek = Weekday(first_jan)
		 select case dayofweek
		 		 case 1 first_thursday_of_year = dateadd("d", 4 ,first_jan)
		 		 case 2 first_thursday_of_year = dateadd("d", 3 ,first_jan)
		 		 case 3 first_thursday_of_year = dateadd("d", 2 ,first_jan)
		 		 case 4 first_thursday_of_year = dateadd("d", 1 ,first_jan)
		 		 case 5 first_thursday_of_year = first_jan
		 		 case 6 first_thursday_of_year = dateadd("d", 6 ,first_jan)
		 		 case 7 first_thursday_of_year = dateadd("d", 5 ,first_jan)
   End Select
end function