Using dates on the X-axis

[Bill Gee]

I generate graphs every now and then which show a year of data.  The data is temperature and water depth.  It all works well, except that the x-axis is marked in days since zero.  I would MUCH rather have the x-axis show actual dates.  It would be enough to show the first of each month.  There are 35000 data points in each graph, so showing every date would not work!

So far I have not found a way to do this.  Can anyone give me any clues?

KST version = 2.0.8 (from Fedora repository)
Fedora 31, 64-bit
Qt = 4.8.7
KDE = whatever version installs to Fedora 31

A short sample of the input data file:

===============
Date,Water Pressure,Barometric Pressure,Water Depth,Temperature 
01/01/19 00:00:00,14.7982,14.3716,0.869,53.623 
01/01/19 00:30:00,14.8026,14.379,0.863,53.623 
01/01/19 01:00:00,14.8028,14.3821,0.857,53.798 
01/01/19 01:30:00,14.8092,14.3938,0.846,53.798 
01/01/19 02:00:00,14.8223,14.4057,0.849,53.798 
01/01/19 02:30:00,14.8288,14.4162,0.841,53.798 
01/01/19 03:00:00,14.8246,14.4162,0.832,53.973 
01/01/19 03:30:00,14.8289,14.4191,0.835,53.973 
01/01/19 04:00:00,14.8246,14.4176,0.829,53.973 
01/01/19 04:30:00,14.8289,14.425,0.823,53.973 
01/01/19 05:00:00,14.8336,14.431,0.820,54.147 
01/01/19 05:30:00,14.8379,14.4368,0.817,54.147 
01/01/19 06:00:00,14.8465,14.4472,0.813,54.147 
01/01/19 06:30:00,14.853,14.4532,0.815,54.147 
01/01/19 07:00:00,14.8596,14.4606,0.813,54.147 
01/01/19 07:30:00,14.8661,14.4739,0.799,54.147 
01/01/19 08:00:00,14.8748,14.4798,0.805,54.147 
01/01/19 08:30:00,14.8771,14.4901,0.788,54.322 
01/01/19 09:00:00,14.8793,14.4946,0.784,54.322 
01/01/19 09:30:00,14.888,14.5035,0.783,54.322
================

In the data wizard, I specify the first line of the file as field names.  In "Date/Time Interpretation" I set

Interpret Field = Date
Formatted String = MM/dd/yy hh:mm:ss
Offset = Relative, 0.00 seconds

In the window for editing a graph, under X-Axis I have tried every combination I can think of for date interpretation and display format.  None of them produce what I want.

Thanks!
-- 
Bill Gee

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