When you say you have "a massive file," I assume that means that you do not have a single variable that summarizes the amount of data for each combination of time point. I think you need to perform 2-D binning of the data first, and then visualize the binned data.
Since SAS 9.2 is now 8 years old, and there have been 7 releases of SAS since then, it is hard to remember what techniques were available back then. For example, if you were using a modern version of SAS, I would recommend that you construct a hexagonal bin plot. Since that won't work in SAS 9.2, I suggest you look into using PROC KDE to count observations in two-dimensional bins.
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