Extract Unique Values From Range

I have data of different accident year. Now I need to identify different Accident Year and use them in Macro to do certain things. For example in the file attached I am using them in Msgbox. Now to acheive that I first extracted unique values using advanced filter on Column C and later use the different value to POP up the Msgbox. (This is achieved). Now I want to skip this part of doing Advance filter to extract unique value. Is there a way I can know unique value of data through the code itself and use them in program. here is what I am doing currently: I have delted the most of the data cause I am concerned with coulumn containing acc_year only.

Sub test()
Columns("A:A").AdvancedFilter Action:=xlFilterCopy, CopyToRange:= Range("C2" _
), Unique:=True
Range("C2").Select
Range(Selection, Selection.End(xlDown)).Select
Selection.Sort Key1:=Range("C3"), Order1:=xlAscending, Header:=xlGuess, _
OrderCustom:=1, MatchCase:=False, Orientation:=xlTopToBottom, _
DataOption1:=xlSortNormal
Range("C3").Select
Do While ActiveCell.Value <> ""
MsgBox ("The Year is " & ActiveCell.Value)
a = ActiveCell.Row
Range("C" & a + 1).Select
Loop
End Sub