What was the difference between northern and southern imports of slaves during the years 1768-1772?

The Southern states imported fewer slaves than the northern states. The Historical Statistics of the United States show that in 1772 only South Carolina alone imported 7,201 slaves when New York only imported 23. From 1771 to 1768 Massachusetts did not import slaves at all and only imported 4 slaves in 1772. Connecticut also had the same patterns it did not import any slaves from 1772 to 1769 and only imported 14 in 1768.