Problem creating a progress bar

Hello,

I have some VBA code that searches keywords through a worksheet and deletes the line where the keyword is found. It does this through a loop. Since this is a lengthy process i have created a progress bar. The thing is, the progress bar works, but i have sort of cheated to make it work. In the part:
UserForm1.ProgressBar1.Value = (progress / 350) * 100
I have divided by 350, but i have merely found this number by trial and error. With this number the progress bar stops a 100% so this is just a temporary fix. I was wondering how i can count the number of times the loop runs so i can put the proper number instead of 350.
BTW i found most of this code on the internet.
Any ideas??

Sub MainScreen()
    Dim calcmode As Long
    Dim ViewMode As Long
    Dim myStrings As Variant
    Dim FoundCell As Range
    Dim I As Long
    Dim myRng As Range
    Dim sh As Worksheet
    Dim progress, total_rows As Variant
    
    progress = 0
    
    'show form
    UserForm1.Show
    
    With Application
        calcmode = .Calculation
        .Calculation = xlCalculationManual
        .ScreenUpdating = False
    End With


    Set sh = ActiveSheet

    Set myRng = sh.Range("A3:M1000")

    myStrings = Array("#DIV/0!", "100.0%", "N/A", "finance")


    With sh


        .Select


        ViewMode = ActiveWindow.View
        ActiveWindow.View = xlNormalView


        .DisplayPageBreaks = False

        'We will search the values in MyRng in this example
        With myRng

            For I = LBound(myStrings) To UBound(myStrings)
                Do
                    Set FoundCell = myRng.Find(What:=myStrings(I), _
                                               After:=.Cells(.Cells.Count), _
                                               LookIn:=xlValues, _
                                               LookAt:=xlWhole, _
                                               SearchOrder:=xlByRows, _
                                               SearchDirection:=xlNext, _
                                               MatchCase:=False)
                    If FoundCell Is Nothing Then
                        Exit Do
                    Else
                        FoundCell.EntireRow.Delete
                    End If
                    'progress bar
                    progress = progress + 1
                    UserForm1.ProgressBar1.Value = (progress / 350) * 100
                    UserForm1.Label1.Caption = CInt((progress / 350) * 100) & "%"
                    DoEvents
                Loop
            Next I
    
    End With

    End With
    
    ActiveWindow.View = ViewMode
    With Application
        .ScreenUpdating = True
        .Calculation = calcmode
    End With
    
    'bring progress bar to the end
    UserForm1.Label1.Caption = "100%"
    UserForm1.ProgressBar1.Value = 100

End Sub