Essentially, two thirds of the stations have no normals! Of course, this still leaves us with
a lot more stations than we had for tmean (goodnorm reported 3316 saved, 1749 deleted) though
still far behind precipitation (goodnorm reported 7910 saved, 8027 deleted).

I suspect the high percentage lost reflects the influx of modern Australian data. Indeed, nearly
3,000 of the 3,500-odd stations with missing WMO codes were excluded by this operation. This means
that, for tmn.0702091139.dtb, 1240 Australian stations were lost, leaving only 278.

This is just silly. I can't dump these stations, they are needed to potentially match with the
bulletin stations. I am now going to try the following:

1. Attempt to pair bulletin stations with existing in the tmin database. Mark pairings in the
database headers and in a new 'Australian Mappings' file. Program auminmatch.for.

2. Run an enhanced filtertmm to synchronise the tmin and tmax databases, but prioritising the
'paired' stations from step 1 (so they are not lost). Mark the same pairings in the tmax
headers too, and update the 'Australian Mappings' file.

3. Add the bulletins to the databases.