The measurement of Newton's constant of gravitation
Ever since Cavendish's famous determination of the mean density of the earth in 1798, a value closely related to Newton's gravitational constant, countless efforts have been made to measure this quantity more precisely.
This graph contains some relevant measurements of big G during the last decade. Green points were measured with a torsion balance. Red points were determined using different methods (beam balance, douple pendulums, & atom interferometer). The gray shaded area gives the 1-sigma interval of the most recent recommended value of G by CODATA.