arrays - ネストされた配列でクラスを使用する

Question

VBA プログラムで構造体の代わりにクラスを使用したいのですが、解決できませんでした。以下は私がやっていることの例であり、アドバイスをいただければ幸いです。クラスはこの種のことには向いていないのかもしれません。

Option Explicit
Public Type xYear
    month(1 To 12) As Double ' Index is the month
End Type
Public Type Company
    Name As String
    City As String
    Sales(2010 To 2020) As xYear ' Index is the year
End Type
Public SuperData(1 To 50) As Company ' An array of companies with monthly sales 
Sub Test_Table()
    Dim Company1_Name As String
    Dim Company1_City As String
    Dim Company1_2011_Sales(1 To 12) As Double
    Dim Company1_2012_Sales(1 To 12) As Double
    Dim Toledo_Sales_Jul_2012 As Double
    ' Test Data
    Company1_Name = "ABC"
    Company1_City = "Toledo"
    Company1_2011_Sales(7) = 1000
    Company1_2012_Sales(7) = 2000
    ' Copy test data into Structure
    SuperData(1).Name = Company1_Name
    SuperData(1).City = Company1_City
    SuperData(1).Sales(2011).month(7) = Company1_2011_Sales(1) ' Jul 2011 sales
    SuperData(1).Sales(2012).month(7) = Company1_2012_Sales(7) ' Jul 2012 sales
    ' Query the structure
    Toledo_Sales_Jul_2012 = City_Sales("Toledo", 7, 2012)
End Sub
Public Function City_Sales(ByRef City As String, ByRef m As Double, ByRef y As Double) As Double
        Dim c As Double
        For c = LBound(SuperData) To UBound(SuperData)
        If City = SuperData(c).City Then
            City_Sales = City_Sales + SuperData(c).Sales(y).month(m)
        End If
    Next
End Function