Column: k_symbol (characterization of the transaction)
Data format: text
Value description: "POJISTNE": stands for insurrance payment
"SLUZBY": stands for payment for statement
"UROK": stands for interest credited
"SANKC. UROK": sanction interest if negative balance
"SIPO": stands for household
"DUCHOD": stands for old-age pension
"UVER": stands for loan payment