In order to better estimate the necessary transactions fees when sending BC I am searching for backward statistics over the last month resp resp last year.
If you want to estimate the fees you need for a transaction, looking for months old data will get you nothing useful.
You can web search for
average fees chart bitcoin and you may get the data, but again, it won't help.
As the others said, you have to look on
https://jochen-hoenicke.de or
https://mempool.space/ since they will give you an image on what is
now in the mempool. And that is most probably unrelated to what was there one week or one month ago.
Then you can decide based on:
* how full mempool is
* how fast the last blocks got mined
* the difficulty vs hash rate (eg if the percent in mempool.space for estimated diff adjustment is >0 then you have to expect faster-than-usual blocks)
* whether you expect the number of transactions-to-come increase or not in the near future
As you can see, all these are basically unrelated to whatever has happened in the past, especially week(s) ago.