Put any arithmetic expression using
            C/R/D/T
            (cumulative confirmed/recovered/death/tested),
            Cc
            (currently confirmed),
            dC/dR/dD/dT/dCc
            (newly confirmed/recovered/death/tested cases/currently confirmed derivation),
            ddC/ddR/ddD/ddT/ddCc
            (second derivation),
            P (population), or D_PAST (daily average total deaths 2010 – 2017) while %=10^2, k=10^3, M=10^6 and X starts from 0.
            Note that `tested` are available for Czechia only.
            
Ex:
            R/(C+R+D): Total recovered ratio.
            dR+dD: Newly closed cases.
            P/C: Every n-th person is confirmed.
            C/P: Nth part of the population is confirmed.
            C%/P: Nth-percent of the population is confirmed.
            CM/P: N people is confirmed in every million of citizens.
            ln(X), log(X, base=10), X^2: Guideline examples.