Jim, corporate taxes as a percentage of the state's budget have been going down for decades!  One giveaway after another--such as the S Corp tax deal given away in return for PERS cuts that were then ruled illegal in the Grand Bargain (I know, the judges are in PERS, but that's another debate).  
Little by little, giveaway by giveaway, corporations have gotten their actual tax bite lower and lower.  Public employees are a handy target, but when it's gotten to the point that corporations themselves actually are suggesting tax increases you know things are truly out of whack.