According to NASA/RSS anomaly data (the reference level is 28.73 kg/m^2) at http://data.remss.com/vapor/monthly_1deg/tpw_v07r01_198801_202101.time_series.txtaverage global water vapor increased about 1.49% per decade from Jan 1988 to Jan 2021 (their most recent report). This is about twice the amount that would occur from just temperature increase and amounts to about 7 molecules of WV added for each molecule of CO2 added.