Your variable named YR_WEEK is obviously a character variable, and it has lots of values, and so each one is plotted.
What you really want is a variable that is numeric — all dates in SAS should be (I would say MUST be) numeric, and dates in SAS are the number of days since 01JAN1960, formatted to be readable. So convert your dates to a SAS numeric variable, format it any way you want, and then the numeric variable ought to plot in a more reasonable way.
How did you create these text strings for YEAR_WK? If we knew that, we could provide code to create a numeric date value in a new variable that will plot properly.
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Paige Miller