If the issue is spacing between your 'dates', it might help to actually use date values and date formats.
GPLOT will fill the amount of space set to create graphs. If your data is sparse and you do not want the graph to be so wide then use goptons to either change the HSIZE or HPIXELS values. Or specify a LENGTH for your Xaxis using an AXIS statement and associating the HAXIS gplot option with that defined axis.
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