Fig. 2

Monthly temporal profiles of the percentage of information volume for each month. The solid, dashed, and dotted lines respectively represent the time series for the national newspapers (the Asahi Shimbun, the Mainichi, the Nikkei, the Sankei Shimbun, and the Yomiuri Shimbun), the regional newspaper (the Chunichi Shimbun), and the local newspaper (the Shinano-Mainichi Shimbun). We defined the information volume as the sum of characters of news articles published in a month. The total number of characters contained in the samples were 553148, 479479, and 1020193 for the national, regional, and local newspapers, respectively