Data for 1989-2020 are available in SAS, Microsoft Excel, and CSV (comma separated values) format.
The SAS files, which have been compressed to facilitate downloading, can be read into other data analysis programs, such as SPSS and STATA. The Windows operating system comes with software for decompressing (unzipping) files. UNIX/LINUX distributions also come with decompressing software. Further guidance for opening a compressed file is available here: http://www.wikihow.com/Open-a-.Zip-File-Without-Winzip.
The accompanying An Introduction to Analyzing the NAWS Public Access Data provides an overview for analyzing NAWSPAD with commonly used software and for calculating design-corrected standard errors using the replicate weights.