how many different codes were used from 1953 to 1958?
6
Code Year Code Year Code Year
A 1927 A1 1955 A2 1981
B 1928 B1 1956 B2 1982
C 1929 C1 1957 C2 1983
CH 1930 CH1 RIEN CH2 RIEN
D 1931 D1 1958 D2 1984
E 1932 E1 1959 E2 1985
F 1933 F1 1960 F2 1986
G 1934 G1 1961 G2 1987
H 1935 H1 1962 H2 1988
I 1936 I1 1963 I2 1989
J 1937 J1 1964 J2 1990
K 1938 K1 1965 K2 1991
L 1939 L1 1966 L2 1992
LL 1940 LL1 RIEN LL2 RIEN
M 1941 M1 1967 M2 1993
N 1942 N1 1968 N2 1994
Ñ 1943 Ñ1 1969 Ñ2 1995
O 1944 O1 1970 O2 1996
P 1945 P1 1971 P2 1997
Q 1946 Q1 1972 Q2 1998
R 1947 R1 1973 R2 1999
S 1948 S1 1974 S2 2000
T 1949 T1 1975 T2 2001
U 1950 U1 1976 U2 2002
V 1951 V1 1977 V2 2003
X 1952 X1 1978 X2 2004
Y 1953 Y1 1979 Y2 2005
Z 1954 Z1 1980 Z2 2006
csv/203-csv/248.tsv