Please don't delete a question because you're not getting the feedback you want.
Since you didn't provide any example data, I'll make some:
%work backwards from the result to create data
end_result=[140 60 30 20 18 18 15];
fun=@(count,pos) repmat(pos,1,count);
days_since_main_event=cell2mat(cellfun(fun,...
num2cell(end_result),num2cell(1:numel(end_result)),...
'UniformOutput',false));
%find the histogram
maxdays=max(days_since_main_event);
counts=histcounts(days_since_main_event,maxdays);
%do an 4th order polynomial fit - replace with actual expected function
p=polyfit(1:maxdays,counts,4);
xfit=linspace(1,maxdays,200);
yfit=polyval(p,xfit);
%plot data and fit in a clean figure
figure(1),clf(1)
plot(1:maxdays,counts,'rd')
hold on
plot(xfit,yfit,'k')
