Although slaves had been sold in the American colonies since at least 1619, slave labor did not come to represent a significant proportion of the labor force in any part of North America until the last quarter of the 17th century. After that time, the numbers of slaves grew exponentially.
A Pharmacologist earns an average salary of $103,686 per year. For the first five to ten years in this position, salary increases sharply, but any additional experience does not have a big effect on pay.
With an average salary of $56,760 in 2013, radiologic technologists earned more than clinical laboratory technicians ($40,240) but slightly less than respiratory therapists ($57,880), and roughly $10K less than diagnostic medical sonographers ($67,170).