events at 2000 athletes). There are two types of qualifying standard: the "A" standard and the "B" standard. Each National Olympic Committee (NOC) may enter up to three athletes who have obtained the "A" standard, or one athlete with the "B" standard. If a NOC has no qualifying athletes in any Olympic athletic event, it may enter one non-qualified athlete – the 100 m is a frequent choice for this type of entry given the brevity of the event. Athletes must achieve the qualifying time without wind-assistance at an officially authorised event within a certain time period, which typically begins from the year prior to the Olympics and extends up to three weeks before the games. The IAAF prohibits entrants who do not reach the age of sixteen in that Olympic year, but there is no upper age limit. The IAAF qualifying standards for the 100 m have become progressively more stringent since 2000. On top of IAAF standards, national governing bodies may apply their own participation restrictions. These principally come in four forms: stricter national qualifying times, reduced time periods for qualifying performances, performances in the event at a national Olympic trials, and decisions of national selection committees. Smaller nations do not typically apply these additional criteria due to the smaller numbers of sprinters eligible to compete. Larger nations, and nations with strong traditions in sprinting, often have long-running histories of Olympic 100 m trials (such as at the United States Olympic Trials). Participation for a country also demands that the athlete hold respective citizenship and is not subject to a competitive ban through anti-doping rules. World Athletics in 2019 announced that, following the inauguration of their World Rankings platform, that in addition to those who achieved the Olympic standard, placing in the top 32 of the rankings will serve as a qualification method for athletes. (For example, if someone comes 3rd in the 100m finals of their national championships in 10.14, if he is 22nd in the World Rankings, he has qualified for the games). Data notes Numbers do not include non-starting athletes. There have been two Olympic 100 m non-starters: Estonia's Reinhold Saulmann in 1920, and Kim Collins in 2012 – the latter was banned from competing by the St. Kitts and Nevis Olympic Committee for defying their orders and leaving the Olympic camp to stay with his wife. Nations are above defined as the competing Olympic