• Open the input file
• Read the file line by line
• For each line use a regex to pull off one or more digits at the end of the line
• use a hash to keep track of how many times that number's occured
• if the regex failed to find a number, increment a counter $missing_count
• at the end of the file, sort the list of keys in the hash by their value and print out your results table

If you need more than that, show what you've tried so far.