Despite the country's Puritan past, the average US citizen has slept with more than 10 people, according to raunchy research into the world's most promiscuous countries. NapLab compiled data from various sources to come up with their list, looking at national sexually tranmitted infection rates, a country's attitudes toward premarital sex and their average number of sex partners, among other criteria. America was declared the 15th most promiscuous country on the planet.