parameter file to get the mortality eg.national life
table data
age
age to get the age specific data
mortality_colname
column name with the mortality rates if it is not
gender specific
gender
gender details to get the gender specific mortality data
Details
Provides the mortality rates as age and gender dependent
Assumes the data contains mortality rate for single year and once
it extracted
per gender will retrieve single value
Age column can consists of range of values, or a particular value
also assumes that the mortality rate for each gender is listed under
the gender column for gender specific values. if the mortality
is not gender specific, the column name should be passed on to the function
if gender is not null, mortality_name will be ignored