President Ronald Reagan, who served from 1981 to 1989, was a self-professed conservative. (AP Photo)

(CNSNews.com) - Self-professed conservatives now outnumber self-professed liberals in the United States, 42 percent to 21 percent, according to a Gallup poll published Monday. Another 37 percent described themselves as moderates.

The percentages are based on Gallup's daily tracking polls conducted from June 1 to Aug. 31 of this year.

The polls show a slight increase in the percentage of conservatives from the last time Gallup reported these numbers. On Aug. 1, Gallup said that in its polling during the first half of 2011, 41 percent of respondents described themselves as conservatives, 21 percent described themselves as liberals, and 36 percent described themselves as moderates.

Over the past two decades, according to Gallup, the percentage of Americans describing themselves as conservative has gradually increased, rising from 36 percent who said they were conservative in 1992.

The percentage who described themselves as liberal rose from 17 percent in 1992 to a high of 22 percent in 2007 and 2008. Since then, the percentage saying they were liberal has held steady at 21 percent.