The file sunspots.txt contains the annual average number of sunspots observed on the surface

of the sun from $1700-2023.($The first value is for the year $1700,$ the second value is for the year

$1701,$ etc.$)$

Generate a time$-$series plot showing how the number of sunspots on the surface of the sun

varies over time. You will notice a cyclical pattern. By visual inspection, estimate the length of

the sunspot cycle, that is$,$ the average number of years from peak to peak.

Additional requirements:

$$ Plot all points as blue dots using the $.$ Marker, except when the year is between $1790$

and $1830.$ During these years, plot the points using the $$x$$ marker and make them red

instead of blue. This period is known as the $$Dalton Minimum$$

$$ Before plotting add the line: plt$.$figure$($figsize$=(20,2),$ dpi$=200)$

This creates a $20$x$2$ inch plot with a resolution of $200$ dots $($pixels$)$ per inch.