Your last graph demonstrates a common data visualization problem. You have dozens of discrete categories, but only 600 pixels to display them. By default, PROC SGPLOT will thin the categories. For 30 or 50 categories you can try to see them all by (1) Making the graph taller, (2) Making the font smaller, and (3) Use FITPOLICY=NONE. For more than 50 categories you can thin (as you've done) or create a plot that shows most frequent categories while grouping the less frequent categories into an "Others" category.