  We present the third instalment of a series of catalogues presenting 12.2-GHz
methanol maser observations made towards each of the 6.7-GHz methanol masers
detected in the Methanol Multibeam (MMB) Survey. The current portion of the
catalogue includes the Galactic longitude region 10 to 20 degrees, where we
detect 47 12.2-GHz methanol masers towards 99 6.7-GHz targets. We compare the
occurrence of 12.2-GHz methanol masers with water maser emission, for which all
6.7-GHz methanol masers in the 6 to 20 degrees longitude range have now been
searched. We suggest that the water masers follow a more complicated
evolutionary scenario than has been found for the methanol and OH masers,
likely due to their different pumping mechanisms. Comparisons of the 6.7-GHz
methanol to OH maser peak flux density ratio and the luminosity of the
associated 12.2-GHz sources suggests that the 12.2-GHz maser luminosity begins
to decline around the time that an OH maser becomes detectable.
