Thats producing a field with the decimal included...
your_search | rex field=_raw "(?<extracted>\s:\s\d+)$"
Yes all of it is what I want, I need to make one more clarification is that when its present its ALWAYS at the END of the line. Its the last string. The rex above is pulling data out in the middle of the line as well which is not desired.
Putting the "\s:\s" into the capture string will include it all -- if that is what you are wanting. This is how I am reading your desired results, else what alacercogitatus provided is right on target.