E (E):


, , -,- , .

-,- -- 20-25 , -- .

( ) ", " [ Felker ea 1977 ]. . - 13% . ( ) 1,098-1,137 /, 1 [ Thurherg ea 1996 ]. ().

299 , 34200 [ Rail ea 1982 ].

293 , 71% [ Fung ea 1986 , Hussain ea 1988 ].

3 , : 2 , 3 4 . -,-. 75% 3/3 . 2/2 . "" 2/2 1:100, 1- 2% .

. , .