The coincides with the period known as the "little ice age" of europe and north america. this provides one piece of evidence that suggests a link between solar activity and the amount of solar energy earth receives.

The Little Ice age coincided with a period known as a Maunder Minimum. This is a period of decreased solar activity and is assessed by the amount of sunspots on the surface of the sun. The Little Ice Age is not a true Ice Age. True ice ages also coincide with periods of decreased solar influence because of the nature of the earth's orbit that changes over time in cycles. Thus is known as Milankovitch cycles. 

Is there a picture of the diagram?