Quarter	Billions Of Ton-Miles
1960-01-01	144.379
1960-04-01	149.677
1960-07-01	140.135
1960-10-01	138.015
1961-01-01	128.899
1961-04-01	140.391
1961-07-01	144.787
1961-10-01	148.918
1962-01-01	143.787
1962-04-01	150.898
1962-07-01	146.365
1962-10-01	150.637
1963-01-01	144.340
1963-04-01	161.503
1963-07-01	154.835
1963-10-01	160.265