what is the difference (in years) between when the royal blue began and the year the crusader began?
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col : operators | named trains | destination | year begun | year discontinued row 1 : baltimore and ohio | capitol limited | chicago, illinois via washington, d.c. and pittsburgh, pennsylvania | 1923 | 1958* row 2 : baltimore and ohio | metropolitan special | st. louis, missouri via washington, d.c. and cincinnati, | ca. 1920 | 1958* row 3 : baltimore and ohio | national limited | st. louis, missouri via washington, d.c. and cincinnati, | 1925 | 1958* row 4 : baltimore and ohio | royal blue | washington, d.c. | 1890 | 1958 row 5 : central railroad of new jersey | blue comet | atlantic city, new jersey | 1929 | 1941 row 6 : reading railroad with the central railroad of new jersey | crusader | philadelphia, pennsylvania | 1937 | 1967 row 7 : reading railroad with the central railroad of new jersey | harrisburg special | harrisburg, pennsylvania |  |  row 8 : reading railroad with the central railroad of new jersey | queen of the valley | harrisburg, pennsylvania |  | 1967 row 9 : reading railroad with the central railroad of new jersey | wall street | philadelphia, pennsylvania |  |  row 10 : reading railroad with the central railroad of new jersey | williamsporter | williamsport, pennsylvania |  |
what is the difference (in years) between when the royal blue began and the year the crusader began?
Operators Named trains Destination Year begun Year discontinued
Baltimore and Ohio Capitol Limited Chicago, Illinois via Washington, D.C. and Pittsburgh, Pennsylvania 1923 1958*
Baltimore and Ohio Metropolitan Special St. Louis, Missouri via Washington, D.C. and Cincinnati, Ohio ca. 1920 1958*
Baltimore and Ohio National Limited St. Louis, Missouri via Washington, D.C. and Cincinnati, Ohio 1925 1958*
Baltimore and Ohio Royal Blue Washington, D.C. 1890 1958
Central Railroad of New Jersey Blue Comet Atlantic City, New Jersey 1929 1941
Reading Railroad with the Central Railroad of New Jersey Crusader Philadelphia, Pennsylvania 1937 1967
Reading Railroad with the Central Railroad of New Jersey Harrisburg Special Harrisburg, Pennsylvania
Reading Railroad with the Central Railroad of New Jersey Queen of the Valley Harrisburg, Pennsylvania 1967
Reading Railroad with the Central Railroad of New Jersey Wall Street Philadelphia, Pennsylvania
Reading Railroad with the Central Railroad of New Jersey Williamsporter Williamsport, Pennsylvania
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