INDIANAPOLIS - Indiana's rate of population growth has fallen for a sixth straight year.

The Indiana Business Research Center at Indiana University said Thursday that U.S. Census Bureau estimates show Indiana's population grew by just 0.32 percent in 2012, but that was still higher than those of each of its adjacent states.

Researchers said sluggish population growth has been the norm in many parts of the country.

Several central Indiana counties remain among the fastest growing in the state, but even their rate of growth is falling off.

While Hamilton County remained the state's fastest-growing county with a 2.2 percent increase last year, that rate falls short of its annual growth rate from 2000 to 2010.

Boone County grew by 2 percent, with Hendricks and Johnson counties showing 1.2 percent growth, ranking fourth and sixth in the state.

Hendricks and Johnson counties also grew below their annual averages from 2000 to 2010.

Hamilton County picked up 6,294 residents in 2012. From 2000 to 2010, the county averaged increased population of 9,181.

Bartholomew County grew by 1.7 percent in, with Tippecanoe County up in population by 1.3 percent.

Madison, Delaware and Wayne counties all posted declines in population. In all, 54 Indiana counties lost population last year.