Been tracking my electric power usage for 7 years...my bill averages about $375/month..I can tell you the largest impact is my a/c. When I replaced my 10 year old compressor with a new, more efficient one, my monthly electric bill dropped 25%
4 years ago I upgraded from a 55gal to a 200gal and hardly noticed any difference But when I go on vacation for 2 weeks, my bill drops 30%.