The absolute bioavailability of a drug, when administered by an extravascular route, is usually less than one (i.e., F< 100%). Various physiological factors reduce the availability of drugs prior to their entry into the systemic circulation. Although drug use and drug market statistics are used to inform and support policies, court decisions, and academic research affecting entire societies, there is currently no way to reliably and directly measure how many people use illegal or recreational psychoactive drugs. Use and abuse of drugs and alcohol by teens is very common and can have serious consequences. In the 15-24 year age range, 50% of deaths (from accidents, homicides, suicides) involve alcohol or drug abuse.Drugs and alcohol also contribute to physical and sexual aggression such as assault or rape.Drug abuse and addiction is less about the type or amount of the substance consumed or the frequency of your drug use, and more about the consequences of that drug use. If your drug use is causing problems in your life—at work, school, home, or in your relationships—you likely have a drug abuse or addiction problem. The factors can be used in cases such as custody, parenting time, and minor guardianships. If you want to change custody or parenting time, it is very important to start with the articles Changing a Custody Order and How a Judge Decides a Motion to Change Parenting Time.