My webpage archief.kohnstamminstituut.nl shows a very long list of publications. In the Database Source Query Builder I have defined to sort the data DESC by year (second column; jaar) and (if applicable) number (third column; rapport). Sorting the second column (jaar) seems to be correct. However, in the third column (rapport), sorting is not correct. In the year 2018, numbers in the third column start with 9-hundreds instead of 1-thousands. How do I correct this?