The following graph shows heavy truck sales since 1967 using data from the BEA. The dashed line is the May 2021 seasonally adjusted annual sales rate (SAAR).
Heavy truck sales really collapsed during the great recession, falling to a low of 180 thousand SAAR in May 2009. Then heavy truck sales increased to a new all time high of 563 thousand SAAR in September 2019.
However heavy truck sales started declining in late 2019 due to lower oil prices.
Heavy truck sales really declined at the beginning of the pandemic, falling to a low of 299 thousand SAAR in May 2020.
Heavy truck sales were at 553 thousand SAAR in May, up from 473 thousand SAAR in April, and up 85% from 299 thousand SAAR in May 2020.