Here is the information noted on the 10 pm news. According to meteorologists at the NWS in Phoenix,

"A COMMONLY ASKED QUESTION IS WHETHER OR NOT RAINFALL DURING THE MONSOON IS CHANGING /OR BECOMING LESS/. BASED ON THE LONG TERM TREND FOR PHOENIX THE ANSWER IS NO. THE DATA SHOW THAT THERE IS GREAT VARIABILITY FROM ONE YEAR TO THE NEXT...AND EVEN ONE DECADE TO THE NEXT. THERE IS ALSO A LONG TERM OSCILLATION WHICH APPEARS IN THE DATA SET...WITH PEAKS IN RAINFALL AMOUNTS /WET/ DURING THE 1910S...1950S AND 1980S...AND TROUGHS /DRY/ DURING THE 1930S...1970S AND THE 2000S."