Here is the graph of the decrease for the orbital period of the binary pulsar, which proves the existence of gravitational waves and gave to Hulse and Taylor the Nobel price in 1993.

Caption
Decrease of the orbital period P (about 7h 45 min) of the binary pulsar PSR B1913+16, measured by the sucessive shifts T(t) of the crossing times at periaster; the continuous curve corrresponds to T(t) = 1/2 (1/P)dP/dt t2 with dP/dt given by the general relativity (reaction to the gravitational waves emission)

Reference:
Taylor J.H. 1993, Testing relativistic gravity with binary and millisecond pulsars, dans General Relativity and Gravitation 1992, eds. R.J. Gleiser, C.N. Kozameh, O.M. Moreschi. Institute of Physics Publishing (Bristol).