Line length report

I have got this far. I am trying to create a report of line lengths based on linetype.

I have built a list that looks like this...

(("CUT4SS" . 859.566) ("CUT4SS" . 862.231) ("CUT4SS" . 927.651) ("CUT6SS" . 1158.48) ("CUT6SS" . 509.903) ("CUT6SS" . 2840.31) ("CUT4SS" . 967.76) ("CUT4SS" . 508.73) ("CUT4SS" . 111.065) ("CUT4SS" . 483.216))

I want to take this list and create a function to create a list of total lengths i.e. the CDR's.

(("CUT6SS" .total length)("CUT4SS" . total length))

I can do the rest but I'm awfull rusty. Brain freeze.

I appreciate the help. Thanks