maximum of `max` data points will be generated.
The `formula` parameter controls the formula used to generate data points.
-Available forumlae:
+Available formulae:
* `interval` - The height of each point represents how long it has been
since the previous post.
many posts were made that day.
* `permonth` - Each point represents a month; the height represents how
many posts were made that month.
-* `peryear` - Each point represents a day; the height represents how
+* `peryear` - Each point represents a year; the height represents how
many posts were made that year.
-The `time` parameter has a default value of "ctime", since forumae use
+The `time` parameter has a default value of "ctime", since formulae use
the creation times of pages by default. If you instead want
them to use the modification times of pages, set it to "mtime".