added function get_years() which returns an object with an value that lists all years and a value that list the amount of publications of every year
added function get_years() which returns an object with an value that lists all years and a value that list the amount of publications of every year

aha01/PubViz,aha01/PubViz,alex-rind/PubViz,fhstp/PubViz,alex-rind/PubViz,fhstp/PubViz