Month Passenger-Miles 1920-01-01 18.7000 1920-02-01 18.5000 1920-03-01 19.0000 1920-04-01 19.5000 1920-05-01 19.6000 1920-06-01 21.0000 1920-07-01 22.1000 1920-08-01 22.7000 1920-09-01 20.5000 1920-10-01 18.8000 1920-11-01 18.3000 1920-12-01 17.9000 1921-01-01 17.1000 1921-02-01 16.7000 1921-03-01 16.2000 1921-04-01 15.6000 1921-05-01 16.1000 1921-06-01 17.2000 1921-07-01 17.8000 1921-08-01 17.8000 1921-09-01 16.9000 1921-10-01 15.5000 1921-11-01 14.8000 1921-12-01 15.1000 1922-01-01 14.6000 1922-02-01 14.6000 1922-03-01 14.2000 1922-04-01 15.2000 1922-05-01 15.3000 1922-06-01 16.8000 1922-07-01 17.4000 1922-08-01 17.7000 1922-09-01 17.3000 1922-10-01 16.1000 1922-11-01 15.5000 1922-12-01 16.4000 1923-01-01 15.4000 1923-02-01 15.4000 1923-03-01 15.1000 1923-04-01 15.6000 1923-05-01 15.7000 1923-06-01 17.6000 1923-07-01 17.6000 1923-08-01 18.0000 1923-09-01 17.3000 1923-10-01 15.6000 1923-11-01 15.2000 1923-12-01 16.2000 1924-01-01 15.1000 1924-02-01 15.0000 1924-03-01 14.7000 1924-04-01 14.7000 1924-05-01 14.8000 1924-06-01 16.7000 1924-07-01 16.4000 1924-08-01 17.1000 1924-09-01 15.9000 1924-10-01 14.3000 1924-11-01 14.1000 1924-12-01 14.7000 1925-01-01 14.4000 1925-02-01 14.3000 1925-03-01 13.4000 1925-04-01 13.5000 1925-05-01 14.2000 1925-06-01 16.1000 1925-07-01 16.1000 1925-08-01 16.8000 1925-09-01 15.7000 1925-10-01 14.2000 1925-11-01 13.7000 1925-12-01 14.3000 1926-01-01 14.0000 1926-02-01 14.0000 1926-03-01 13.1000 1926-04-01 13.5000 1926-05-01 13.8000 1926-06-01 15.4000 1926-07-01 15.5000 1926-08-01 15.8000 1926-09-01 15.1000 1926-10-01 13.6000 1926-11-01 13.2000 1926-12-01 13.9000 1927-01-01 13.4000 1927-02-01 13.3000 1927-03-01 12.4000 1927-04-01 13.0000 1927-05-01 13.3000 1927-06-01 14.5000 1927-07-01 14.8000 1927-08-01 14.8000 1927-09-01 14.3000 1927-10-01 12.8000 1927-11-01 12.5000 1927-12-01 13.1000 1928-01-01 12.7000 1928-02-01 12.5000 1928-03-01 11.8000 1928-04-01 12.4000 1928-05-01 12.3000 1928-06-01 14.1000 1928-07-01 13.9000 1928-08-01 14.2000 1928-09-01 13.8000 1928-10-01 12.2000 1928-11-01 12.0000 1928-12-01 12.7000 1929-01-01 12.2000 1929-02-01 12.6000 1929-03-01 12.0000 1929-04-01 11.9000 1929-05-01 12.1000 1929-06-01 13.7000 1929-07-01 13.4000 1929-08-01 14.0000 1929-09-01 13.0000 1929-10-01 11.6000 1929-11-01 11.3000 1929-12-01 12.3000 1930-01-01 11.4000 1930-02-01 11.5000 1930-03-01 10.6000 1930-04-01 10.8000 1930-05-01 11.1000 1930-06-01 12.4000 1930-07-01 12.2000 1930-08-01 12.4000 1930-09-01 11.6000 1930-10-01 10.4000 1930-11-01 10.4000 1930-12-01 10.6000 1931-01-01 10.1000 1931-02-01 10.5000 1931-03-01 9.70000 1931-04-01 10.5000 1931-05-01 10.7000 1931-06-01 11.6000 1931-07-01 11.3000 1931-08-01 11.3000 1931-09-01 11.0000 1931-10-01 9.40000 1931-11-01 9.50000 1931-12-01 9.90000 1932-01-01 9.30000 1932-02-01 9.60000 1932-03-01 9.30000 1932-04-01 9.10000 1932-05-01 9.70000 1932-06-01 10.2000 1932-07-01 10.5000 1932-08-01 10.5000 1932-09-01 10.8000 1932-10-01 9.20000 1932-11-01 9.00000 1932-12-01 10.0000 1933-01-01 8.70000 1933-02-01 8.90000 1933-03-01 8.00000 1933-04-01 9.10000 1933-05-01 9.40000 1933-06-01 10.9000 1933-07-01 11.4000 1933-08-01 11.7000 1933-09-01 11.8000 1933-10-01 11.0000 1933-11-01 9.80000 1933-12-01 10.9000 1934-01-01 9.90000 1934-02-01 10.3000 1934-03-01 10.0000 1934-04-01 10.5000 1934-05-01 10.1000 1934-06-01 11.6000 1934-07-01 11.8000 1934-08-01 12.2000 1934-09-01 11.7000 1934-10-01 10.8000 1934-11-01 10.0000 1934-12-01 11.3000 1935-01-01 10.4000 1935-02-01 10.7000 1935-03-01 9.90000 1935-04-01 10.3000 1935-05-01 10.1000 1935-06-01 11.5000 1935-07-01 11.5000 1935-08-01 12.2000 1935-09-01 11.6000 1935-10-01 10.5000 1935-11-01 10.7000 1935-12-01 11.8000