Transport Topics reported heavy-duty truck sales climbed 15% in April from a year earlier and surpassed the 20,000 mark for the fifth time in eight months after reaching that level only one other time since 2006.

According to Transport Topics, U.S. retail sales of Class 8 trucks increased to 20,509 last month, a jump from 17,776 in April 2014 but a 0.6% downtick from 20,625 in March.

Transport Topics reported April’s growth was not as strong as the respective 23%, 28% and 25% gains posted in January through March, but still marked the 20th consecutive month of year-over-year improvement in sales volumes.

To view the full Transport Topics report, click here.