Rhino Records made a series of CDs of Billboard Top Ten songs for various years. I wonder, if you summed every sequence of 52 consecutive weeks, how many songs would show in those Rolling Top Tens that never made a calendar year Top Ten?
Being nerdy, I might suggest this to Rhino: package the Top Ten of the chart’s first 52 weeks, and thereafter make a new package each time ten songs not in a previous package have reached the Rolling Top Ten.