 The percentage of joint physical versus sole physical custody varies between countries.In a comparative survey from 2005/06, covering children ages 11 to 15, it was highest in Sweden with 17% and lowest in Turkey and the Ukraine with only 1%.Studies suggest that joint custody may significantly contribute to a child's wellbeing, with lower rates of mental health issues and substance abuse, better school performance, better physical health and better family relationships as compared to children in households where one parent has sole physical custody.