Not Reliable. Numbers sometimes normal, sometimes stop randomly while increasing

Not Reliable. Numbers sometimes normal, sometimes stop randomly while increasing. This is particularly not good for my site, as the aim is to talk about test scores, etc. It’s like, “yes, our average pass rate is 64%.” Wonderful. [Proceeds to reload the page] “Oops, I mean our average pass rate is 49%.” By all means who am I to complain when I have zero clue how to code, but why something as simple as a counter is not reliable is somewhat perplexing to me.