Environmental Engineering Problems and Solutions

| 1913 | 100 | 1920 | 207 | 1927 | 186 | 1934 | 167 | 1941 | 211 | 1948 | 345 | 1955 | 469 |
| 1914 | 92 | 1921 | 166 | 1928 | 188 | 1935 | 166 | 1942 | 222 | 1949 | 352 | 1956 | 491 |
| 1915 | 95 | 1922 | 155 | 1929 | 191 | 1936 | 172 | 1943 | 229 | 1950 | 375 | 1957 | 509 |
| 1916 | 131 | 1923 | 186 | 1930 | 185 | 1937 | 196 | 1944 | 235 | 1951 | 401 | 1958 | 525 |
| 1917 | 167 | 1924 | 186 | 1931 | 168 | 1938 | 197 | 1945 | 239 | 1952 | 416 | 1959 | 548 |
| 1918 | 159 | 1925 | 183 | 1932 | 141 | 1939 | 197 | 1946 | 262 | 1953 | 431 | 1960 | 559 |
| 1919 | 159 | 1926 | 185 | 1933 | 148 | 1940 | 203 | 1947 | 313 | 1954 | 446 | 1961 | 568 |
| 1913 = 100 | Monthly | ||||||||||||
| Jan. | Feb. | Mar. | Apr. | May | June | July | Aug. | Sept. | Oct. | Nov. | Dec. | Annual Average | |
| 1962 | 571 | 573 | 575 | 576 | 579 | 580 | 583 | 586 | 586 | 586 | 584 | 584 | 580 |
| 1963 | 584 | 585 | 586 | 586 | 588 | 590 | 596 | 602 | 602 | 604 | 602 | 603 | 594 |
| 1964 | 604 | 604 | 606 | 607 | 609 | 612 | 615 | 616 | 617 | 617 | 617 | 617 | 612 |
| 1965 | 616 | 621 | 622 | 621 | 621 | 626 | 628 | 630 | 633 | 634 | 633 | 634 | 627 |
| 1966 | 635 | 641 | 643 | 649 | 652 | 656 | 653 | 655 | 656 | 655 | 655 | 655 | 650 |
| 1967 | 656 | 657 | 659 | 660 | 666 | 671 | 673 | 678 | 681 | 684 | 685 | 687 | 672 |
| 1968 | 692 | 695 | 698 | 701 | 710 | 718 | 721 | 729 | 741 | 747 | 747 | 755 | 721 |
| 1969 | 764 | 770 | 780 | 790 | 791 | 798 | 792 | 799 | 796 | 797 | 801 | 802 | 790 |
| 1970 | 802 | 801 | 802 | 813 | 827 | 834 | 848 | 851 | 857 | 862 | 866 | 866 | 836 |
| 1971 | 875 | 877 | 905 | 913 | 933 |