fars_summarize_years: Summarize fars record by year
In CorradoLanera/weektwo: Course: Building R Packages, week 2

Description Usage Arguments Value Note Examples

Compute the number of records are present for fars for each year (columns) and month (rows).

1	fars_summarize_years(years, path = ".")

`years`	(num) An integer vector of years (or an object cohercible to it) containing the years of fars files of interest.
`path`	(chr) path to the fars file

A data frame with a number of column equals to the number of (valid) years passed as input (plus one for the months) and one row each month included in the corresponding fars files. The data frame is filled with the number of records included for the corresponding year and month.

If a year not present in the data is provided, a warning is returned and no column is created for it.

## Not run: 
   file_path <- system.file("tests", "testthat", package = "weektwo")

   fars_summarize_years(c(2013, 2014), path = file_path)

   fars_summarize_years(c(2012, 2013, 2014), path = file_path)

## End(Not run)