Monthly Millions Of Hours
1926-01-01 2.87000
1926-02-01 2.62000
1926-03-01 2.96000
1926-04-01 3.11000
1926-05-01 3.42000
1926-06-01 3.32000
1926-07-01 3.37000
1926-08-01 3.26000
1926-09-01 3.24000
1926-10-01 3.30000
1926-11-01 2.98000
1926-12-01 2.97000
1927-01-01 2.96000
1927-02-01 2.80000
1927-03-01 3.27000
1927-04-01 3.25000
1927-05-01 3.51000
1927-06-01 3.38000
1927-07-01 3.51000
1927-08-01 3.42000
1927-09-01 3.41000
1927-10-01 3.69000
1927-11-01 3.33000
1927-12-01 3.18000
1928-01-01 3.23000
1928-02-01 3.18000
1928-03-01 3.48000
1928-04-01 3.48000
1928-05-01 3.84000
1928-06-01 3.68000
1928-07-01 3.84000
1928-08-01 3.80000
1928-09-01 3.67000
1928-10-01 3.91000
1928-11-01 3.58000
1928-12-01 3.62000
1929-01-01 3.48000
1929-02-01 3.21000
1929-03-01 3.73000
1929-04-01 3.84000
1929-05-01 4.07000
1929-06-01 4.05000
1929-07-01 4.27000
1929-08-01 4.11000
1929-09-01 4.03000
1929-10-01 4.27000
1929-11-01 3.91000
1929-12-01 3.81000
1930-01-01 3.61000
1930-02-01 3.56000
1930-03-01 3.99000
1930-04-01 4.06000
1930-05-01 4.20000
1930-06-01 3.94000
1930-07-01 4.02000
1930-08-01 3.91000
1930-09-01 3.81000
1930-10-01 4.10000
1930-11-01 3.80000
1930-12-01 3.82000
1931-01-01 3.70000
1931-02-01 3.47000
1931-03-01 3.87000
1931-04-01 3.87000
1931-05-01 4.16000
1931-06-01 3.97000
1931-07-01 4.15000
1931-08-01 3.83000
1931-09-01 3.63000
1931-10-01 3.81000
1931-11-01 3.59000
1931-12-01 3.54000
1932-01-01 3.44000
1932-02-01 3.28000
1932-03-01 3.50000
1932-04-01 3.51000
1932-05-01 3.64000
1932-06-01 3.40000
1932-07-01 3.46000
1932-08-01 3.25000
1932-09-01 3.24000
1932-10-01 3.62000
1932-11-01 3.38000
1932-12-01 3.37000
1933-01-01 3.35000
1933-02-01 2.98000
1933-03-01 3.29000
1933-04-01 3.27000
1933-05-01 3.50000
1933-06-01 3.52000
1933-07-01 3.73000
1933-08-01 3.69000
1933-09-01 3.58000
1933-10-01 3.81000
1933-11-01 3.62000
1933-12-01 3.55000
1934-01-01 3.61000
1934-02-01 3.29000
1934-03-01 3.86000
1934-04-01 3.88000
1934-05-01 4.08000
1934-06-01 4.01000
1934-07-01 4.06000
1934-08-01 4.02000
1934-09-01 3.83000
1934-10-01 4.01000
1934-11-01 3.71000
1934-12-01 3.71000
1935-01-01 3.75000
1935-02-01 3.52000
1935-03-01 4.09000
1935-04-01 4.01000
1935-05-01 4.17000
1935-06-01 4.01000
1935-07-01 4.02000
1935-08-01 3.96000
1935-09-01 3.95000
1935-10-01 4.34000
1935-11-01 4.08000
1935-12-01 4.07000
1936-01-01 4.03000
1936-02-01 3.66000
1936-03-01 4.20000
1936-04-01 4.31000
1936-05-01 4.58000
1936-06-01 4.46000
1936-07-01 4.60000
1936-08-01 4.52000
1936-09-01 4.44000
1936-10-01 4.83000
1936-11-01 4.69000
1936-12-01 4.86000
1937-01-01 4.68000
1937-02-01 4.29000
1937-03-01 5.03000
1937-04-01 4.91000
1937-05-01 5.18000
1937-06-01 5.04000
1937-07-01 5.02000
1937-08-01 4.82000
1937-09-01 4.72000
1937-10-01 5.13000
1937-11-01 4.55000
1937-12-01 4.42000
1938-01-01 4.20000
1938-02-01 3.90000
1938-03-01 4.30000
1938-04-01 4.10000
1938-05-01 4.21000
1938-06-01 4.09000
1938-07-01 4.21000
1938-08-01 4.24000
1938-09-01 4.16000
1938-10-01 4.58000
1938-11-01 4.32000
1938-12-01 4.50000
1939-01-01 4.46000
1939-02-01 4.88000
1939-03-01 4.67000
1939-04-01 4.49000
1939-05-01 4.65000
1939-06-01 4.63000
1939-07-01 4.69000
1939-08-01 4.63000
1939-09-01 4.70000
1939-10-01 5.09000
1939-11-01 4.88000
1939-12-01 4.80000
1940-01-01 4.66000
1940-02-01 4.52000
1940-03-01 4.84000
1940-04-01 4.77000
1940-05-01 5.04000
1940-06-01 4.86000