Before posting these questions on the baut forum, I checked the Bautforum for previous posts, the most relevant one seems to be this query in aid of a seemingly dead-end contentious debate, which was of little help.
Following a reference link from Wikipidia's page on "Gravitational Constant", note this excerpt from the abstract:
"...G stands mysteriously alone, its history being that of a quantity which is extremely difficult to measure and which remains virtually isolated from the theoretical structure of the rest of physics. Several attempts aimed at changing this situation are now underway, but the most recent experimental results have once again produced conflicting values of G and, in spite of some progress and much interest, there remains to date no universally accepted way of predicting its absolute value..."
The measurements seem surprisingly sketchy when considering that most Universal Constants can be measured to the 8th to 10th decimal.
For reasons out of the blue, I took it into my head to place the year that Gravitational Constant measurements were taken in relation to the sunspot cycle. Needless to say, this data is thin to the point of being laughable, but still - an amusing thought:
Gravitational Constant measurements on the Solar Cycle, coinciding with the dates of the measurements:
Luther 1982 Torsion pendulum 6:6726 § 0:0005 75
Fitzgerald 1995 Torsion balance 6:6656 § 0:0006 90
Schwarz 1998 Free fall 6:6873 § 0:0094 1400
K¨undig 2002 Beam balance 6:67407 § 0:00022 200
Notice the smaller result during low sunspot activity.