Offshore support vessels have rounded off a tough 2017 with a rise in the global number of drilling rigs, one of the ships’ most important employers.

December’s 3.4% month-on-month increase in working rigs follows 2017’s largest decline of 10.1% in November.

This 3.4% rise is also slightly larger than many of the monthly percentage changes for all of last year, either up or down, although one of the largest increases was in September with 8.6%.