The graph shows the decline in size of the US Military relative to the population of the United States. Over 2 percent of the population was in the military during Korea. Even with the buildup during Vietnam participation was less than 2 percent of the population.
Today only about .5 a percent of the US Population is in the military. This refutes two assertions:
The left says we have too large a military, but it is much smaller today as a percent of total population.
The right says we have too any people working for government, but the US Military is much smaller than before.