I have a .xls file for each day of the year from 1955 to 2023. The file naming is like: day_1955_1.tif.xls, day_1955_2.tif.xls....so on, 365 files for non leap years and 366 days files for leap years. In naming convention 1955_1, 1955_2, 1955 is the year, and 1, 2 represent day 1(January 1, 1955) and day 2 (january 2).