In parsing this data, we attempted to keep as much usable data as possible without distorting the results. Roman numerals were transformed into arabic numbers. In case two years are given (e.g. 1549/50), the first and second year were alternated. If the year was given as a time span (e.g. 1650-1660) we computed the average of both values and rounded to the larger number when necessary. For the estimated dates we decided that omitting the records altogether would have shrunk the database considerably. So we just deleted the estimation markers like ‘ca.’ and kept the years. This produced larger spikes every 50 years and smaller ones every 5 and 10 years, but these can be explained easily when interpreting the results.