Monthly Millions Of Hours
1921-07-01 10.1800
1921-08-01 9.15000
1921-09-01 8.95000
1921-10-01 10.2300
1921-11-01 8.76000
1921-12-01 7.50000
1922-01-01 8.38000
1922-02-01 8.48000
1922-03-01 8.98000
1922-04-01 7.20000
1922-05-01 7.91000
1922-06-01 8.50000
1922-07-01 15.0000
1922-08-01 25.1200
1922-09-01 30.7400
1922-10-01 28.6700
1922-11-01 25.1700
1922-12-01 24.5400
1923-01-01 22.8600
1923-02-01 20.8700
1923-03-01 20.3100
1923-04-01 17.2100
1923-05-01 17.4700
1923-06-01 16.4500
1923-07-01 16.5300
1923-08-01 16.3600
1923-09-01 16.3800
1923-10-01 17.0500
1923-11-01 14.9300
1923-12-01 12.6300
1924-01-01 14.4000
1924-02-01 14.8300
1924-03-01 12.6700
1924-04-01 10.2300
1924-05-01 10.2300
1924-06-01 9.74000
1924-07-01 10.1200
1924-08-01 10.8300
1924-09-01 12.0700
1924-10-01 12.6700
1924-11-01 12.0900
1924-12-01 13.0400
1925-01-01 14.4800
1925-02-01 11.7400
1925-03-01 10.1700
1925-04-01 9.06000
1925-05-01 9.97000
1925-06-01 9.74000
1925-07-01 10.8600
1925-08-01 11.6200
1925-09-01 12.5700
1925-10-01 13.9100
1925-11-01 13.7600
1925-12-01 12.9600
1926-01-01 13.0400
1926-02-01 13.8900
1926-03-01 12.0500
1926-04-01 10.3300
1926-05-01 11.0600
1926-06-01 10.4600
1926-07-01 11.7500
1926-08-01 12.3600
1926-09-01 14.2600
1926-10-01 14.7000
1926-11-01 14.2800
1926-12-01 14.4700
1927-01-01 13.4600
1927-02-01 11.8400
1927-03-01 10.4600
1927-04-01 10.4000
1927-05-01 11.5500
1927-06-01 10.1300
1927-07-01 10.7800
1927-08-01 10.9300
1927-09-01 11.8800
1927-10-01 12.0000
1927-11-01 10.6200
1927-12-01 10.5600
1928-01-01 10.5700
1928-02-01 9.09000
1928-03-01 9.04000
1928-04-01 8.41000
1928-05-01 8.95000
1928-06-01 8.57000
1928-07-01 9.76000
1928-08-01 10.1200
1928-09-01 11.2000
1928-10-01 11.3800
1928-11-01 10.0900
1928-12-01 9.41000
1929-01-01 10.9300
1929-02-01 10.8300
1929-03-01 9.87000
1929-04-01 8.64000
1929-05-01 9.59000
1929-06-01 9.24000
1929-07-01 9.97000
1929-08-01 10.1800
1929-09-01 11.2000
1929-10-01 11.4300
1929-11-01 9.40000
1929-12-01 10.6800
1930-01-01 10.0100
1930-02-01 7.62000
1930-03-01 7.33000
1930-04-01 6.53000
1930-05-01 7.30000
1930-06-01 6.60000
1930-07-01 6.91000
1930-08-01 6.92000
1930-09-01 6.98000
1930-10-01 6.96000
1930-11-01 6.21000
1930-12-01 5.48000
1931-01-01 5.33000
1931-02-01 4.91000
1931-03-01 5.54000
1931-04-01 4.64000
1931-05-01 5.04000
1931-06-01 4.52000
1931-07-01 5.10000
1931-08-01 4.83000
1931-09-01 4.78000
1931-10-01 4.54000
1931-11-01 4.23000
1931-12-01 3.87000
1932-01-01 4.06000
1932-02-01 3.83000
1932-03-01 4.06000
1932-04-01 2.95000
1932-05-01 3.14000
1932-06-01 2.81000
1932-07-01 3.23000
1932-08-01 3.05000
1932-09-01 3.63000
1932-10-01 3.94000
1932-11-01 3.38000
1932-12-01 3.90000
1933-01-01 3.03000
1933-02-01 3.58000
1933-03-01 2.68000
1933-04-01 2.70000
1933-05-01 3.18000
1933-06-01 3.14000
1933-07-01 3.88000
1933-08-01 3.58000
1933-09-01 3.86000
1933-10-01 3.43000
1933-11-01 3.21000
1933-12-01 3.88000
1934-01-01 3.52000
1934-02-01 5.18000
1934-03-01 4.12000
1934-04-01 3.02000
1934-05-01 3.30000
1934-06-01 3.27000
1934-07-01 3.65000
1934-08-01 3.45000
1934-09-01 3.90000
1934-10-01 3.59000
1934-11-01 3.26000
1934-12-01 3.81000
1935-01-01 5.15000
1935-02-01 4.02000
1935-03-01 3.50000
1935-04-01 2.98000
1935-05-01 3.40000
1935-06-01 3.77000
1935-07-01 3.82000
1935-08-01 3.78000
1935-09-01 4.29000
1935-10-01 4.20000
1935-11-01 3.87000
1935-12-01 4.82000
1936-01-01 6.28000
1936-02-01 9.00000
1936-03-01 6.11000
1936-04-01 4.36000
1936-05-01 4.36000
1936-06-01 3.93000
1936-07-01 4.89000
1936-08-01 4.83000
1936-09-01 5.23000
1936-10-01 5.49000
1936-11-01 5.35000
1936-12-01 5.65000
1937-01-01 7.05000
1937-02-01 6.87000
1937-03-01 5.47000
1937-04-01 4.63000
1937-05-01 5.17000
1937-06-01 4.92000
1937-07-01 5.49000
1937-08-01 5.10000
1937-09-01 5.31000
1937-10-01 5.11000
1937-11-01 4.22000
1937-12-01 4.43000
1938-01-01 4.26000
1938-02-01 3.76000
1938-03-01 3.66000
1938-04-01 3.16000
1938-05-01 3.27000
1938-06-01 3.19000
1938-07-01 3.87000
1938-08-01 3.61000
1938-09-01 4.74000
1938-10-01 4.76000
1938-11-01 4.36000
1938-12-01 4.08000
1939-01-01 4.44000
1939-02-01 4.29000
1939-03-01 3.84000
1939-04-01 3.40000
1939-05-01 3.64000
1939-06-01 3.71000
1939-07-01 4.20000
1939-08-01 4.05000
1939-09-01 5.31000
1939-10-01 5.58000
1939-11-01 4.82000
1939-12-01 4.75000
1940-01-01 6.41000
1940-02-01 5.37000
1940-03-01 4.25000
1940-04-01 3.79000
1940-05-01 4.16000
1940-06-01 4.33000
1940-07-01 4.80000
1940-08-01 5.16000
1940-09-01 5.67000
1940-10-01 5.45000
1940-11-01 5.68000
1940-12-01 6.08000
1941-01-01 6.26000
1941-02-01 5.84000
1941-03-01 6.82000
1941-04-01 5.38000
1941-05-01 6.71000
1941-06-01 7.63000
1941-07-01 8.24000
1941-08-01 8.52000
1941-09-01 8.86000
1941-10-01 9.16000
1941-11-01 8.38000
1941-12-01 8.81000
1942-01-01 9.54000
1942-02-01 9.08000
1942-03-01 9.52000
1942-04-01 9.08000
1942-05-01 10.8300
1942-06-01 10.2700
1942-07-01 12.4300
1942-08-01 14.0400
1942-09-01 16.1600