CSV file sort and group by year

I cannot find how this can be done so any help would be appreciated, this will complete my move to Hugo from Jekyll

I have a csv file containing the following columns and rows

An Officer and a Spy,by,Robert Harris,2019-01-24
Confessions of Felix Krull Confidence Man,by,Thomas Mann,2019-01-10
Thanks for Nothing,by,Jack Dee,2018-12-31
Please Mister Postman,by,Alan Johnson,2018-12-26
The Brooklyn Follies,by,Paul Auster,2018-12-22

I am using the following

{{ $url := "reading.csv" }}
{{ $sep := "," }}
{{ range $i, $r := getCSV $sep $url  }}  
    {{ index $r 0 }} {{ index $r 1 }} {{ index $r 2 }}
{{ end }}`

This gives me a list of the data in the file. I would like to be able to group by year using the year-read column.

I have the exact same question. Did you manage to work it out @Keith?