The numbers of how things affect the release of dopamine.
Matthew Vere summarizes the book Dopamine Nation by Anna Lembke:
The neurotransmitter dopamine plays a crucial role in the brain’s reward processing, with studies showing that it contributes more to the motivation for rewards than to the pleasure of receiving them. For a rat in a box, chocolate increases the release of dopamine by 55%, sex by 100%, nicotine by 150%, cocaine by 225%, and amphetamines, the active ingredient in speed, meth, MDMA, and Adderall (used to treat ADHD and narcolepsy) by 1000%. According to one study, abusing dopamine levels alters our ability to delay gratification, with addicts referring to their futures as only nine days long, compared to 4.7 years for the non-addicted participants.
Even though amphetamines are an order of magnitude more potent than sex, sex has an unusual property in that it can be prolonged for hours, whereas the highest high of cocaine only lasts a few minutes.