You could use str2Con to convert your string into a container.
Str text = '2013: 1512 2014: 25222 2015: 35233 2016: 1623233';
container data;
data = str2con(text,' ');
print conPeek(data,1) + ' ' + int2str(conPeek(data,2));
pause;
Extra benefit is that you actually get your data in a structure that is also a little easier to work with.