section_path: History/Late 20th century
section_name: Late 20th century
paragraph_text: Late 20th century
  
  During the mid-20th century, the number of new antibiotic substances introduced for medical use increased significantly. From 1935 to 1968, 12 new classes were launched. However, after this, the number of new classes dropped markedly, with only two new classes introduced between 1969 and 2003.