From a page about geometric percent decreases, explaining that that kind of graph represents an unchanging loss of a percentage of the measured value every interval:
The sequence 100, 50, 25, 12.5, … is a geometric sequence. The common ratio is 1/2. To go from term to term, you keep multiplying by 1/2 (i.e., dividing by 2).
The graph of the sequence 100, 50, 25, 12.5, … is shown below:
The eye of the bee-holder... ugh. This image actually made me sadder.