Old can radiocarbon dating
The gramophone sat in your parlor and certainly couldn't be carried along with you and your earbobs. When 78 rpm records first appeared on the market, they were very rare.
When they became popularly available, you could find them everywhere; but then the technology changed and they became rare again. Archaeologists investigate trash, not shop window displays, so we measure things when they are discarded; in this example, we're going to use junkyards.
Larger percentages of artifact types are illustrated with longer bar snippets and smaller percentages with shorter bar snippets.
A good source of information about how to make charts in Excel is Ted French's Excel Chart Tutorial (for several different versions of Excel).
What this step does is create a visual representation of the qualities of the artifacts, and their co-occurrence at different junkyards.
Notice that this figure does not mention what kind of artifacts we're looking at, it just groups similarities.
The gramophone dragged a needle in a spiral groove at a rate of 78 revolutions per minute (rpm).
We count the types of musical recording methods found in each of our junkyard samples, and then work out the percentages.