There are 17 statistics on Semistandard tableaux in the database:
(and possibly some waiting for verification)

St000101Semistandard tableaux ⟶ ℤ
The cocharge of a semistandard tableau.
St000102Semistandard tableaux ⟶ ℤ
The charge of a semistandard tableau.
St000103Semistandard tableaux ⟶ ℤ
The sum of the entries of a semistandard tableau.
St000112Semistandard tableaux ⟶ ℤ
The sum of the entries reduced by the index of their row in a semistandard tableau.
St000116Semistandard tableaux ⟶ ℤ
The major index of a semistandard tableau obtained by standardizing.
St000170Semistandard tableaux ⟶ ℤ
The trace of a semistandard tableau.
St000173Semistandard tableaux ⟶ ℤ
The segment statistic of a semistandard tableau.
St000174Semistandard tableaux ⟶ ℤ
The flush statistic of a semistandard tableau.
St000736Semistandard tableaux ⟶ ℤ
The last entry in the first row of a semistandard tableau.
St000737Semistandard tableaux ⟶ ℤ
The last entry on the main diagonal of a semistandard tableau.
St000739Semistandard tableaux ⟶ ℤ
The first entry in the last row of a semistandard tableau.
St001401Semistandard tableaux ⟶ ℤ
The number of distinct entries in a semistandard tableau.
St001407Semistandard tableaux ⟶ ℤ
The number of minimal entries in a semistandard tableau.
St001408Semistandard tableaux ⟶ ℤ
The number of maximal entries in a semistandard tableau.
St001409Semistandard tableaux ⟶ ℤ
The maximal entry of a semistandard tableau.
St001410Semistandard tableaux ⟶ ℤ
The minimal entry of a semistandard tableau.
St001805Semistandard tableaux ⟶ ℤ
The maximal overlap of a cylindrical tableau associated with a semistandard tableau.