"Figure 2: Airline Freight, Express, and Mail Revenue Ton-Miles",,,,,,,,,,,,
,1990,1991,1992,1993,1994,1995,1996,1997,1998,1999,2000,2001
Air (Improved BTS)1,10.42,9.96,10.99,11.54,12.03,12.72,13.76,13.9,14.14,14.5,15.81,13.288
Air (NTS)2,9.064,8.86,9.82,10.675,11.803,12.52,12.861,13.601,13.84,14.202,14.983,13.088
Air (Eno)3,10.42,9.96,10.99,11.54,12.03,12.72,13.76,13.9,14.14,14.5,15.81,15.18
Sources:,,,,,,,,,,,,
"1 BTS, Office of Airline Information, Air Carrier Traffic Statistics Monthly, p. 2; FAA supplemtary statistics.",,,,,,,,,,,,
"2 BTS, National Transportation Statistics, 2003, Table 1-44. ",,,,,,,,,,,,
"3 Eno Transportation Foundation, Transportation in America, 2002, p. 42. ",,,,,,,,,,,,