This figure comprises a bar graph showing the number of antibiotic classes discovered in each decade. The horizontal axis is labelled decade and marked from 1890s to 2010s in decade intervals. The vertical axis is labelled number of antibiotic classes discovered/patented and is marked from 0 to 10 in intervals of 1. The number of classes discovered is given above each bar. The highest number of antibiotic classes discovered were in the 1940s (7 classes) and the 1950s (9 classes) after this antibiotic discovery declined. On the right of the graph the last three decades (1990-2010s) are shaded in grey and this section of the graph is labelled no registered classes of antibiotics discovered after 1984.