Airborne observations of high-resolution infrared absorption, recorded between 1978 and 2005, are used to retrieve column amounts of H216O, H217O, H218O and HDO. Observations span a wide range of years, seasons and latitudes, all made with essentially the same spectrometer system. A spectral optimal estimator fitting technique, SFIT2, has been used uniformly to analyze all the data. The latitudinal distributions of H216O, H217O and H218O are similar and much like those from other observations (e.g., SPARC (Kley et al., 2000)). The column of HDO above 13 km exhibits a distribution with latitude that is much less pronounced. From 1978 to 2005 the long-term increase in the column of Northern Hemisphere H216O above 13 km is found to be 1.16 ¿ 0.4%/year, consistent with previous observations. HDO is found to decrease by about 0.4%/year during the same period. In low latitudes, from 35¿S to 35¿N, large depletions of HDO relative to H216O, δD (-460 ¿ 21?), and H218O relative to H216O (-104 ¿ 47?) are determined. δD shows an unexpected trend of enhanced depletion of about 5--6? per year for the period from 1978 to 2005.