Why is it they used to use a blue screen, and now they seem to exclusively use a green screen in movies etc?

** info **
Other colors are sometimes used instead of blue, including magenta (The Matrix), yellow (some 1970s episodes of Doctor Who, and Song of the South), orange (Apollo 13) and red (Air Force One or Predator). The choice of color depends on the subject and specific technique used. Blue is normally used for people because human skin has very little blue color to it. Green is used because digital cameras retain more detail in the green color channel and it requires less light. Magenta screens are often used with model photography where the model contains both blue and green components, and yellow was used in Doctor Who because a number of props and costume items contained both blue and green.