for ratio in 1881 see http://www.ee.surrey.ac.uk/Contrib/manx/famhist/fnames/sn1881.htm
4 cubbon:1 crebbin families but still a common Manx name

The name has been around for a bit as even in 1659 John Crebbin,was presented for sleeping in the Church: promised reformation.
(see http://www.ee.surrey.ac.uk/Contrib/manx/jmmuseum/d139.htm)