How come we experience so much more inflation than deflation? in other words, why does our buying power decrease far more often than it increases?

hints :

• inflation increases the nominal amount of tax on added value, good for countries balance sheets
• inflation decreases the real value of sovereign debts
• a company will never lower its prices as long as sales do not plunge
• energy actors only look at natural gas prices when it raises, never when it comes down

you could add your own items to the list, it's a long one.