This graph is from Beyond Oil: the Threat to Food and Fuel in the Coming Decades by John Gever et. al., 3rd edition, 1991, University Press of Colorado, Niwot, Colorado, pg. 79. By 1980, the portion of labor done in the economy by humans was reduced to 0.17%.
Today, fuel and fuel-derived capital do most of the work necessary to produce output. The output produced per worker-hour, called productivity, is thereby expanded tremendously. It might appear that laborers are working harder to produce more goods and services, but in reality these workers, including farmers, are controlling more energy to produce output: they are subsidized by fuels drawn from the environment. When we compare the manufacturing output produced per worker-hour to the amount of fuel used directly to subsidize each worker (ignoring for the moment indirect subsidies like automotive gasoline, home heat, and so forth), it is clear that productivity is closely related to the level of fuel subsidies over the last seventy years. pg. 80.