If we look at the 2007 annual report of the Portable Antiquities Scheme (published at the end of 2009) we find a number of disturbing statistics. Eighty eight percent (in terms of object numbers) of the items the Scheme is recording (Table 7, p. 277) comes from the servicing of artefact hunting, only 12% of the Scheme's activities concerns non-collecting members of the public - who foot the bill. The monthly average of finds reported had dropped from the 2006 values by nearly a third (Table 2c), findspot accuracy was appalling (Table 5a) with 80% of the finds with no National Grid Reference at all, an additional 7% had only four figure NGRs (next to useless for many archaeological purposes).
The 391 records of finds (Table 2a) had resulted from reports made by 358 finders, 256 were "metal detectorists", while 102 were "others". That means (assuming each accidental finder reported one find) that each Welsh "metal detectorist" was responsible for 1.1 records.
Table 6b however notes that metal detecting clubs in Wales have "555+" members. So less than half of these were coming forward with anything, and the vast majority of those that did, came forward with a single item.