Ruby：读取xls文件的内容并获取每个单元格信息

This is the link of a XLS file. I am trying to use Spreadsheet gem to extract the contents of the XLS file. In particular, I want to collect all the column headers like (Year, Gross National Product etc.). But, the issue is they are not in the same row. For example, Gross National Income comprised of three rows. I also want to know how many row cells are merged to make the cell 'Year'. is the link of a XLS file. I am trying to