Hey, Jay. I think we only have the actions of the legal issuers as valid data to go by--not their public propaganda. What independent organizations are there who monitor counterfeit money par-volume? I don't think there are objective organizations.
So instead, using as a measure the types of activity by the legal issuers to deter counterfeit tokens by the US fed, I conclude that they have had ever increase concerned over the ability of paper currency to fulfill the needs of authenticity for the past 15 years or so.
Paper money in the US now includes an embedded stip of plastic within the paper. There is now a watermark within US bills. There is a 'constelation' of markers on most bills, that embedded software in high-end printers capable of duplicating the images of notes, will recognise and refuse to copy. There may be more new additions I don't know about.
This is an ongoing concern as the fed attempts to stay ahead of capable technology in the hands of privateers at home, overseas and by hostile nations.