I'm wondering what sort of regex I could use to match the last occurence of a set of 4 digits in my url.

My url is being formatted like this

```
/ARTIST/ALBUM-4 DIGITS-EXTRA STUFF

```

In the url, "4 DIGITS" will be the last possible occurence of 4 digits together. The thing is the ALBUM may contain sets of 4 digits, so it needs to match the last occurrence in the url. 

Basically I need my rewrite rule to act as follows

```
RewriteRule ^(.*)/(.*)-(.* MATCH LAST OCCURENCE OF 4 DIGITS)-(.*)?$ album.php?artist=$1&album=$2&releaseyear=$3&EXTRA=$4

```

Is there any way to do this?