Create a vector of numerical maturities in years
Maturities(DataYields, Economies, UnitYields)
Vector containing all observed maturities expressed in years
matrix containing all yields of the system (JxT,if the model is single-country-based or CJxT if the model is multy-country-based)
vector containing names of all the economies of the system
(i) "Month": if maturity of yields are expressed in months or (ii) "Year": if maturity of yields are expressed in years