What the most popular and least popular numbers used for PINs? The answer is here.
In this heatmap image above, the x-axis depicts the left two digits from  to  and the y-axis depicts the right two digits from  to . The bottom left is 0000, and the top right is 9999. Color is used to represent frequency. The higher frequency occurences are yellow to white hot, and the lower frequency occurences are red, through dark red to black.