Month	Millions Of Hours
1921-07-01	10.9800
1921-08-01	10.9100
1921-09-01	10.5400
1921-10-01	10.4200
1921-11-01	10.0900
1921-12-01	10.5500
1922-01-01	10.3400
1922-02-01	9.33000
1922-03-01	10.2600
1922-04-01	9.85000
1922-05-01	10.2200
1922-06-01	10.3500
1922-07-01	10.6900
1922-08-01	10.6500
1922-09-01	10.2200
1922-10-01	10.1700
1922-11-01	10.1400
1922-12-01	10.7700
1923-01-01	10.6900
1923-02-01	9.68000
1923-03-01	10.6800
1923-04-01	10.1600
1923-05-01	10.6600
1923-06-01	10.5600
1923-07-01	11.1100
1923-08-01	11.1600
1923-09-01	10.6600
1923-10-01	10.7300
1923-11-01	10.2700
1923-12-01	10.7600
1924-01-01	10.8200
1924-02-01	10.0000
1924-03-01	10.5100
1924-04-01	10.2600
1924-05-01	10.5900
1924-06-01	10.3700
1924-07-01	10.9100
1924-08-01	10.8900
1924-09-01	10.3700
1924-10-01	10.3600
1924-11-01	9.92000
1924-12-01	10.8500
1925-01-01	10.6800
1925-02-01	9.53000
1925-03-01	10.3300
1925-04-01	10.0900
1925-05-01	10.3500
1925-06-01	10.2400
1925-07-01	10.7900
1925-08-01	10.7300
1925-09-01	10.3100
1925-10-01	10.3700
1925-11-01	9.94000
1925-12-01	10.6400
1926-01-01	10.4100
1926-02-01	9.44000
1926-03-01	10.3000
1926-04-01	9.99000
1926-05-01	10.2200
1926-06-01	10.1400
1926-07-01	10.6600
1926-08-01	10.5400
1926-09-01	10.2700
1926-10-01	10.2000
1926-11-01	9.88000
1926-12-01	10.6700
1927-01-01	10.3800
1927-02-01	9.27000
1927-03-01	10.1600
1927-04-01	9.85000
1927-05-01	10.0400
1927-06-01	9.90000
1927-07-01	10.4700
1927-08-01	10.4300
1927-09-01	9.93000
1927-10-01	9.80000
1927-11-01	9.44000
1927-12-01	10.1500
1928-01-01	9.93000
1928-02-01	9.16000
1928-03-01	9.72000
1928-04-01	9.32000
1928-05-01	9.63000
1928-06-01	9.58000
1928-07-01	10.1200
1928-08-01	9.98000
1928-09-01	9.47000
1928-10-01	9.50000
1928-11-01	9.06000
1928-12-01	9.67000
1929-01-01	9.70000
1929-02-01	8.72000
1929-03-01	9.56000
1929-04-01	9.17000
1929-05-01	9.52000
1929-06-01	9.49000
1929-07-01	9.94000
1929-08-01	9.96000
1929-09-01	9.44000
1929-10-01	9.50000
1929-11-01	9.10000
1929-12-01	9.84000
1930-01-01	9.65000
1930-02-01	8.25000
1930-03-01	9.29000
1930-04-01	8.92000
1930-05-01	9.11000
1930-06-01	8.85000
1930-07-01	9.22000
1930-08-01	9.14000
1930-09-01	8.50000
1930-10-01	8.50000
1930-11-01	8.09000
1930-12-01	8.58000
1931-01-01	8.35000
1931-02-01	7.45000
1931-03-01	8.13000
1931-04-01	7.80000
1931-05-01	7.88000
1931-06-01	7.61000
1931-07-01	7.95000
1931-08-01	7.81000
1931-09-01	7.42000
1931-10-01	7.31000
1931-11-01	6.92000
1931-12-01	7.33000
1932-01-01	7.06000
1932-02-01	6.53000
1932-03-01	6.87000
1932-04-01	6.51000
1932-05-01	6.61000
1932-06-01	6.35000
1932-07-01	6.50000
1932-08-01	6.36000
1932-09-01	6.05000
1932-10-01	5.98000
1932-11-01	5.80000
1932-12-01	6.25000
1933-01-01	5.93000
1933-02-01	5.40000
1933-03-01	5.80000
1933-04-01	5.49000
1933-05-01	5.67000
1933-06-01	5.74000
1933-07-01	5.89000
1933-08-01	5.96000
1933-09-01	5.82000
1933-10-01	5.88000
1933-11-01	5.50000
1933-12-01	5.96000
1934-01-01	5.78000
1934-02-01	5.31000
1934-03-01	5.82000
1934-04-01	5.57000
1934-05-01	5.80000
1934-06-01	5.71000
1934-07-01	5.97000
1934-08-01	6.00000
1934-09-01	5.68000
1934-10-01	5.78000
1934-11-01	5.42000
1934-12-01	6.02000
1935-01-01	5.90000
1935-02-01	5.26000
1935-03-01	5.72000
1935-04-01	5.61000
1935-05-01	5.77000
1935-06-01	5.66000
1935-07-01	5.92000
1935-08-01	5.97000
1935-09-01	5.65000
1935-10-01	5.72000
1935-11-01	5.50000
1935-12-01	6.18000
1936-01-01	6.17000
1936-02-01	5.91000
1936-03-01	6.01000
1936-04-01	5.79000
1936-05-01	5.90000
1936-06-01	5.82000
1936-07-01	6.28000
1936-08-01	6.22000
1936-09-01	6.04000
1936-10-01	6.19000
1936-11-01	5.89000
1936-12-01	6.70000
1937-01-01	6.54000
1937-02-01	5.82000
1937-03-01	6.32000
1937-04-01	6.11000
1937-05-01	6.19000
1937-06-01	6.13000
1937-07-01	6.54000
1937-08-01	6.44000
1937-09-01	6.20000
1937-10-01	6.16000
1937-11-01	5.86000
1937-12-01	6.50000
1938-01-01	6.21000
1938-02-01	5.46000
1938-03-01	5.96000
1938-04-01	5.70000
1938-05-01	5.70000
1938-06-01	5.71000
1938-07-01	6.01000
1938-08-01	5.90000
1938-09-01	5.76000
1938-10-01	5.66000
1938-11-01	5.47000
1938-12-01	6.12000
1939-01-01	5.81000
1939-02-01	5.23000
1939-03-01	5.72000
1939-04-01	5.50000
1939-05-01	5.63000
1939-06-01	5.65000
1939-07-01	6.01000
1939-08-01	5.98000
1939-09-01	5.71000
1939-10-01	5.65000
1939-11-01	5.38000
1939-12-01	6.07000
1940-01-01	6.00000
1940-02-01	5.34000
1940-03-01	5.67000
1940-04-01	5.44000
1940-05-01	5.50000
1940-06-01	5.48000