The chart above is from the Gallup Poll. It shows Trump's monthly job approval ratings for all of 2018. Gallup questioned 72,453 adults nationwide between January 22nd of 2018 and January 10th of 2019. The margin of error is 1 point.
Trump started 2018 with a job approval of only 38%. Although he reached the mid-forties a few times (with a high of 45% in June), he averaged only 40% approval for the year. That's very low. Part of that is because his rating went down significantly at the end of the year, and is currently only 37% (probably due to his shutting down the government).
