This graph shows the percentage anomaly over time in top-of-atmosphere observations of Earth's albedo.  Percentages are relative to the mean global value of ~0.29.  Measurements were gathered from March 1, 2000 - December 31, 2011 by the Clouds and Earth's Radiant Energy System (CERES) instruments of NASA's Earth observing satellite network.
Robert Simmon and Norman Loeb
<a rel="nofollow" class="external free" href="https://earthobservatory.nasa.gov/images/84499/measuring-earths-albedo">https://earthobservatory.nasa.gov/images/84499/measuring-earths-albedo</a>