Market: markets currently have two taxes, transaction's tax, applied for sold items, and broker's fee for non immediate orders, which are set at 1.5% and 1% respectively. To create an environment more competitive for Citadels, we plan on increasing the transaction tax to 2.5% and the broker's fee to 5-6%. Players trading in citadels will still receive the transaction tax, but the broker's fee will be at the complete discretion of the owner. To avoid confusion for the owner, the broker relations skill will not affect player set broker's fee in Citadels.
But on one of the support pages
it states that the Transaction Tax has remained at 1.0% for Accounting Level 5 and that is confirmed by my characters who can all still get 1.00% Transaction Tax in NPC stations and Citadels.
The following graph that you cite is compelling:Top sinks and faucets over time
though recall that in February / March / April the Transaction Tax divided by Trade was still 1.00%, as expected. Since then, on this graph, there has been not notable shift in the Transaction Tax line through the summer and autumn or any sort of step that would indicate a sudden change in the Transaction Tax rate.
Also, surely Trade by now would be back or close to February levels? On your data it is still about 39% below. However, if we assume the Transaction Tax rate is actually 1.00% of Trade (because the main traders have Accounting Level 5) then the actual Trade is at the same level as February.