KANSAS CITY — The percentage of total area planted to biotechnology (G.M.O.) varieties of corn and soybean in 2018 was unchanged from 2017, the U.S. Department of Agriculture said in its recent annual Acreage report.

The U.S.D.A. said 92% of total planted corn area in 2018 was comprised of G.M.O. varieties, the same percentage as in 2017. Based on estimated total planted corn area of 89,128,000 acres, that would be about 81,997,760 acres, compared with 2017 when total planted area was 90,167,000 acres, equating to 82,953,640 G.M.O. acres at the same 92% rate.

For 2018, farmers planted 2% of their acres to insect-only resistant G.M.O. varieties of corn (including bacillus thuringiensis [Bt] only) compared with 3% in 2017, 10% to herbicide-only resistant varieties compared with 12% last year and 80% to “stacked” varieties (containing both insect and herbicide resistant genes), up from 77% in 2017.

Of the 13 states listed, the biggest increases in G.M.O. acres were in Ohio, up four percentage points to 86%, and Illinois, up three points at 95%. The largest declines were two percentage points each in Michigan at 85% and Texas at 95%. Changes in all other states were no greater than 1 percentage point. Kansas, Nebraska and South Dakota had the highest percentage of G.M.O. corn at 96% with Michigan the lowest at 85%.

Soybean acres planted to G.M.O. varieties accounted for 94% of total planted area, also equal to 2017, the U.S.D.A. said. All the G.M.O. soybean area was for herbicide resistance. Soybean area planted to G.M.O. varieties would equal about 84,183,580 acres out of total plantings of 89,557,000 acres, compared with 84,733,480 acres in 2017 out of total planted area of 90,142,000 acres.

G.M.O. planted soybean varieties increased by four percentage points to 91% in Missouri and by two points to 96% in Nebraska with changes in all other states no greater than 1 point higher or lower. Of the 14 states listed, Mississippi had the highest percentage of G.M.O. planted soybeans at 99%, with Indiana, Missouri and Ohio the lowest at 91%.

Farmers planted 94% of total upland cotton area to G.M.O. varieties, down from 96% last year, including insect-only, herbicide-only and stacked gene varieties, the U.S.D.A. said.

The U.S.D.A. reports G.M.O. planted area only for corn, soybeans and cotton. There are no approved G.M.O. varieties, and thus none planted, of wheat or most other field crops included in the report.