Rents in Manhattan, Brooklyn and Queens trickled up last month even as the outer boroughs saw an increase in available apartments.

The report released Thursday by the real estate group MNS found that Manhattan had the highest average rents in August at $3,975, a 0.34% increase from July when prices were $3,843.

All types of the borough's apartments rose between August 2014 and last month, including non-doorman studio units, which went from $2,412 last year to $2,630 in August 2015.

A drop in inventory in Manhattan was a major factor for higher rental prices. MNS said the number of available borough units went down 2.91% from 8,663 apartments in July 2015 to 8,411 units last month.

SoHo had the fewest available apartments last month with 179.

Over in Brooklyn, average rents went up slightly, 0.26%, over the year going from $2,741 in August 2014 to $2,748 this year. Boerum Hill had the highest rent increase in the borough going from $2,785 to $3,017 between last August and August 2015, according to MNS.

The number of available units in Brooklyn has shot up recently, growing 1.69% since July 2015 and in neighborhoods like Bushwick, Crown Heights, and Park Slope, inventory levels surged between two- to- four times the amount in August 2014, the report said.

Queens had a larger inventory increase in August with 1,194 rental units, a 16.6% jump from the 1,024 apartments in July. Rents in the borough increased 2.12% from $2,104.13 in July 2015 to $2,148 in August 2015. Long Island City was the most expensive neighborhood in the borough with studios renting for $2,516 and two-bedrooms going for $3,882, according to MNS.