## 3 Material and Methods
### Data Collection  
Every year, research consulting firms GlobeScan and the Sustainability Institute conduct online surveys to study the recognition of leadership in sustainability. Around 700 sustainability experts from the private sector, government, NGOs, and academic and research sectors from over 70 countries participate in the survey [31]. We collected sustainability reports from global sustainability leader companies that are listed in the top 10 rankings in the survey from 2011 to 2020. The list of the survey reports is summarized in Appendix A. A total of 23 companies are included in the top 10 list, but only six companies issued separate or integrated sustainability reports every year from 2011 to 2020. Table 1 shows the names and rankings of the top 10 companies from 2011 to 2020. The six companies covered in this study are numbered in the first column of the table.  
Sustainability reports for the six companies were downloaded in PDF files via their websites or Google search. A total of 60 reports, 10 reports from each of the six companies, were collected. The list of companies and their sustainability reports studied in this paper are summarized in Appendix B. The PDF files typically contain not only text but also tables and images. Since this study aims to analyze textual data only, we extracted text blocks using PyMuPDF [32], one of the PDF-handling libraries in Python. We chose PyMuPDF among many libraries because this library supports decryption of the document and different text-extracting formats such as 'text', 'block', 'words', 'html', and 'JSON'. In addition, text blocks including less than 10 words were eliminated to exclude titles and a bunch of single words that were not part of the sentences.  
The description materials for the 17 SDGs were also downloaded in PDF files from the SDG Compass website. To analyze sustainability reports in a larger framework, 17 SDGs  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline
**Company Name** & **Country** & **2011** & **2012** & **2013** & **2014** & **2015** & **2016** & **2017** & **2018** & **2019** & **2020** \\ \hline Apple & US & & & & & & & 9 & & \\ (1) BASF & Germany & & & & & 9 & & 7 & & 10 & \\ Coca Cola & US & & & 9 & & & & & & & \\ Co-operative & (unknown) & 10 & & & & & & & 8 & 6 & 6 \\ Danone & France & & & & & & & & & & \\ General Electric & US & 2 & 3 & 5 & 8 & 8 & 9 & 7 & & & \\ Google & US & & & & & & 10 & & & & \\ (2) IKEA & Sweden & & & & & 6 & 4 & 4 & 4 & 3 & 3 \\ Interface & US & 3 & 2 & 3 & 3 & 3 & 3 & 3 & 3 & 4 & 4 \\ (3) Marks \& Spencer & UK & 5 & 6 & 6 & 4 & 4 & 8 & 5 & 5 & 8 & \\ Microsoft & US & & & & & & & & & 9 \\ Nature & Brazil & 6 & 7 & 10 & 6 & 5 & 7 & 5 & 5 & 5 & 5 \\ (4) Nestle & Switzerland & & & & & 5 & 7 & 6 & 6 & 7 & 7 & 8 \\ NIKE & US & & 8 & 8 & 7 & 10 & & 7 & & & \\ Novo Nordisk & Denmark & 9 & 9 & & & & & & & & \\ Orsted & Denmark & & & & & & & & & & 10 \\ Patagonia & US & 7 & 4 & 2 & 2 & 2 & 2 & 2 & 2 & 2 & 2 \\ Puma & Germany & & & & 7 & 10 & & & & & & \\ Siemens & Germany & & 10 & & & & & & 5 & 6 & 9 & 7 \\ Tesla & US & & & & & & & & & & 10 & & \\ (5) Toyota & Japan & 8 & & & & & & & & & & 10 & & \\ Unilever & UK & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\ (6) Walmart & US & 4 & 5 & 4 & 9 & & & & & 10 & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Summary of corporate sustainability leader rankings from 2011 to 2020.  
were condensed into six categories that reflect different perspectives of human needs [33]. Table 2 shows the six condensed categories and the SGDs in each category.