SQL Server 2008 :: Return Fiscal Year Based On YYYY-week Format

I have a table where hours are being loaded in a weekly basis. The YearWeek is populated when the data is loaded. The value format of the Year Week is 2015-39, 2015-41, etc. I need to calculate the total hours per Fiscal Year.For example, week '2015-39' will be return FY15 and week '2015-41' will return FY16, and so on. By extracting the year, I can do a group by and have total hours for each year.

Currently, I have it working by splitting the value into year and week and then looping through each year and week, so I can assign the totals to the corresponding FY.select sum(hours) as total, yearweek from tablename group by yearweek...Then I loop through using C#.I can return the FY using an actual date,how to do it for year-week format for any given year.

select CASE
WHEN CAST(GETDATE() AS DATE) >
SMALLDATETIMEFROMPARTS(DATEPART(YEAR,GETDATE()),09,30,00,000)
THEN
DATEPART(YEAR,GETDATE()) + 1 ELSE DATEPART(YEAR,GETDATE())
END AS FY