According to the Regulatory Studies Center of George Washington University,

the number of total pages published in the CFR [Code of Federal Regulations] annually provides a sense of the volume of existing regulations with which American businesses, workers, consumers, and other regulated entities must comply.

The dataset published by the Center provides a consistent measure of the total number of CFR pages for each year from 1950 through 2019, and for 2020 through July 9. Armed with those numbers, I computed the annual rate of increase in the size of the CFR under each administration, from Eisenhower’s to Trump’s (as of July 9, 2020). The result is shown below.

It is no surprise that Trump’s administration was the least heavy-handed. Nor is it surprising that each Democrat administration was generally more heavy-handed than its GOP predecessor. The surprising exception is Clinton’s regime, which was better than Bush I’s, and was second only to Trump’s in its regulatory austerity.