In the 1960s manufacturing accounted for 27% of the usa's gdp. today ) manufacturing's portion of the us gdp has significantly increased (b) manufacturing's portion of the us gdp is about the same as it was in the 1960s (c) manufacturing's portion of the us gdp is about 80% of what it was in the 1960s (d) manufacturing's portion of the us gdp is less than half of what it was in the 1960s