Natural resources: sand and gravel for the less developed countries

6.1527% 1940 0.416663 2.400023 2.3623% 1939 0.398121 2.511801 -1.5482% 1938 0.883559 1.131786 -1.5312% 1937 0.088874 11.251890 3.9669% 1936 0.270975 3.690379 3.2811% 1934 1.820996 0.549150 8.9328% 1933 0.047457 21.071721 -2.6088% 1932 0.097952 10.209057 -11.5407% 1931 1.710558 0.584605 2.3623% 1939 1.336884 0.748008 -1.5482% 1938 0.066503 15.036961 -1.5312% 1937 1.746602 0.572540 3.9669% 1936 0.533907 1.872984 3.2811% 1934 0.945770 1.057340 8.9328% 1933 0.067546 14.804716 -2.6088% 1932 0.833321 1.200018 -11.5407% 1931

admits