Counting in columns

Please refer to the attachment.

My question concerns column D, specifically in D I want to determine the number of occurrences of the values in C. For example, how many times does 1531 occur? I would prefer not to sort the data.

As seen, the formula (for each cell), eg D1 =COUNT(C1,C$1:C$45) doesn’t work.

Any suggestions greatly appreciated.

Grant.