VB.Net - Get Weeks In a Year

Public Function GetWeeksInYear(ByVal dayofsunday As DateTime) As Integer

     Dim dayofthursday As DateTime = dayofsunday.AddDays(-3)
     Dim yearno As Integer = dayofthursday.Year
     Dim firstday As DateTime = "01-Jan-" & yearno.ToString

     Dim totalweeks As Integer = 0

     If firstday.DayOfWeek = DayOfWeek.Thursday Then
         totalweeks = 53
     ElseIf Date.IsLeapYear(yearno) = True _
              And firstday.DayOfWeek = DayOfWeek.Wednesday Then
         totalweeks = 53
     Else
         totalweeks = 52
     End If

     Return totalweeks
End Function