Month	Millions Of Hours
1921-07-01	24.5300
1921-08-01	26.0100
1921-09-01	26.2100
1921-10-01	29.7400
1921-11-01	26.8300
1921-12-01	24.4900
1922-01-01	24.5000
1922-02-01	24.1200
1922-03-01	27.2000
1922-04-01	22.7400
1922-05-01	24.7600
1922-06-01	25.4500
1922-07-01	24.7100
1922-08-01	26.8800
1922-09-01	29.2200
1922-10-01	32.5100
1922-11-01	32.4500
1922-12-01	32.7000
1923-01-01	33.3100
1923-02-01	30.1600
1923-03-01	33.8600
1923-04-01	31.8000
1923-05-01	32.9200
1923-06-01	31.4500
1923-07-01	31.7600
1923-08-01	32.8100
1923-09-01	32.0000
1923-10-01	34.9700
1923-11-01	32.2400
1923-12-01	29.4200
1924-01-01	30.7600
1924-02-01	29.9200
1924-03-01	30.0700
1924-04-01	27.1700
1924-05-01	27.8600
1924-06-01	26.1600
1924-07-01	27.1800
1924-08-01	28.1200
1924-09-01	29.5500
1924-10-01	32.1400
1924-11-01	29.3000
1924-12-01	29.7700
1925-01-01	30.3100
1925-02-01	26.8800
1925-03-01	27.8000
1925-04-01	26.7300
1925-05-01	27.7700
1925-06-01	27.5500
1925-07-01	28.7500
1925-08-01	29.8000
1925-09-01	30.2000
1925-10-01	33.0500
1925-11-01	30.7600
1925-12-01	30.3300
1926-01-01	29.5400
1926-02-01	27.6100
1926-03-01	30.2200
1926-04-01	28.3300
1926-05-01	29.0700
1926-06-01	28.6200
1926-07-01	30.0000
1926-08-01	30.5000
1926-09-01	31.3800
1926-10-01	33.3400
1926-11-01	31.6000
1926-12-01	31.3300
1927-01-01	29.8900
1927-02-01	27.2100
1927-03-01	29.7900
1927-04-01	27.8800
1927-05-01	28.6500
1927-06-01	27.8500
1927-07-01	27.6300
1927-08-01	29.3400
1927-09-01	29.5500
1927-10-01	31.4000
1927-11-01	27.7000
1927-12-01	26.9900
1928-01-01	26.4700
1928-02-01	25.4400
1928-03-01	27.4800
1928-04-01	25.6800
1928-05-01	27.4100
1928-06-01	26.2600
1928-07-01	26.9800
1928-08-01	28.5800
1928-09-01	28.4700
1928-10-01	31.4600
1928-11-01	28.2900
1928-12-01	26.4000
1929-01-01	27.6800
1929-02-01	26.3900
1929-03-01	27.6600
1929-04-01	26.5700
1929-05-01	27.9700
1929-06-01	26.7500
1929-07-01	27.9400
1929-08-01	28.8800
1929-09-01	28.2200
1929-10-01	31.0800
1929-11-01	27.0500
1929-12-01	25.5900
1930-01-01	25.9100
1930-02-01	22.8900
1930-03-01	24.0400
1930-04-01	23.5700
1930-05-01	24.2300
1930-06-01	22.5500
1930-07-01	23.2400
1930-08-01	23.2700
1930-09-01	22.9100
1930-10-01	24.8800
1930-11-01	21.4000
1930-12-01	20.1700
1931-01-01	19.9100
1931-02-01	17.7800
1931-03-01	19.7700
1931-04-01	19.3900
1931-05-01	19.7200
1931-06-01	19.1800
1931-07-01	19.8900
1931-08-01	19.0900
1931-09-01	18.3400
1931-10-01	19.6600
1931-11-01	17.0400
1931-12-01	16.4400
1932-01-01	15.9100
1932-02-01	15.1200
1932-03-01	16.4700
1932-04-01	14.9600
1932-05-01	14.4200
1932-06-01	13.9400
1932-07-01	13.7900
1932-08-01	14.1300
1932-09-01	14.9000
1932-10-01	16.8400
1932-11-01	14.8700
1932-12-01	14.9400
1933-01-01	13.9200
1933-02-01	13.3200
1933-03-01	13.6700
1933-04-01	13.3600
1933-05-01	14.4800
1933-06-01	14.9600
1933-07-01	15.9400
1933-08-01	16.2500
1933-09-01	16.0700
1933-10-01	16.8400
1933-11-01	15.5800
1933-12-01	14.9100
1934-01-01	15.7300
1934-02-01	15.0800
1934-03-01	17.2600
1934-04-01	15.3000
1934-05-01	16.1000
1934-06-01	15.9200
1934-07-01	15.8500
1934-08-01	16.3600
1934-09-01	16.0100
1934-10-01	16.9100
1934-11-01	15.2100
1934-12-01	15.2200
1935-01-01	16.3400
1935-02-01	15.0400
1935-03-01	16.2300
1935-04-01	15.2000
1935-05-01	15.4900
1935-06-01	15.4600
1935-07-01	15.3100
1935-08-01	15.9500
1935-09-01	16.1100
1935-10-01	18.2100
1935-11-01	16.4800
1935-12-01	16.4400
1936-01-01	17.7600
1936-02-01	18.9000
1936-03-01	17.9200
1936-04-01	17.2900
1936-05-01	17.5300
1936-06-01	17.2300
1936-07-01	18.2800
1936-08-01	18.2600
1936-09-01	18.5600
1936-10-01	20.7000
1936-11-01	19.2300
1936-12-01	20.0500
1937-01-01	20.0900
1937-02-01	19.0200
1937-03-01	20.3900
1937-04-01	18.8300
1937-05-01	19.1000
1937-06-01	18.6000
1937-07-01	19.2000
1937-08-01	18.8500
1937-09-01	18.9000
1937-10-01	20.1600
1937-11-01	17.4100
1937-12-01	16.9300
1938-01-01	15.9000
1938-02-01	14.1200
1938-03-01	15.5400
1938-04-01	14.3100
1938-05-01	14.3000
1938-06-01	14.4000
1938-07-01	14.9200
1938-08-01	15.5400
1938-09-01	15.9600
1938-10-01	17.6900
1938-11-01	16.2000
1938-12-01	16.2000
1939-01-01	15.8300
1939-02-01	14.7600
1939-03-01	16.3000
1939-04-01	14.6800
1939-05-01	15.3400
1939-06-01	15.8100
1939-07-01	15.9600
1939-08-01	16.6800
1939-09-01	17.9000
1939-10-01	19.8200
1939-11-01	18.1000
1939-12-01	17.1200
1940-01-01	18.6200
1940-02-01	16.6000
1940-03-01	16.9200
1940-04-01	16.3200
1940-05-01	17.0400
1940-06-01	16.7500