From the Cran Repository Policy:
Packages should be of the minimum necessary size. Reasonable compression should be used for data (not just .rda files) and PDF documentation: CRAN will if necessary pass the latter through qpdf.
As a general rule, neither data nor documentation should exceed 5MB (which covers several books). A CRAN package is not an appropriate way to distribute course notes, and authors will be asked to trim their documentation to a maximum of 5MB.
Where a large amount of data is required (even after compression), consideration should be given to a separate data-only package which can be updated only rarely (since older versions of packages are archived in perpetuity).
Similar considerations apply to other forms of “data”, e.g., .jar files.
1 GB may not be feasible for CRAN. At the very least, it would have to be incorporated into a separate package, and you would probably have to come up with a plan for incremental updates. Otherwise, updating the existing package to include 2018 data next year would require another 1 GB download for people and more than double the storage required for the package by CRAN mirrors.