Universities in the Leiden Ranking 2023 As Figure 1 shows, the number of universities in the Leiden Ranking keeps increasing. Like in the last three editions of the ranking, a university needs to have at least 800 fractionally counted publications in the most recent four-year time window to be included in the ranking. This year 1411 universities meet this criterion, 93 more than last year and 235 more than in 2020.