COUNTIF/SUMPRODUCT(?) to create a matrix from data

This looks horrible. It is horrible. But... it does seem to work... I couldn't think of a prettier way to do it!!

Someone will do it with a punchy one-line formula, and put me to shame!!!

Formula:

=IFERROR(SUMPRODUCT(

(INDEX(data!$F$6:$P$6,,MATCH(output!$D6,data!$F$5:$P$5,0)):INDEX(data!$F$23:$P$23,,MATCH(output!$D6,data!$F$5:$P$5,0))<>"")*

(INDEX(data!$F$6:$P$6,,MATCH(output!$D6,data!$F$5:$P$5,0)-1):INDEX(data!$F$23:$P$23,,MATCH(output!$D6,data!$F$5:$P$5,0)-1)<>

INDEX(data!$F$6:$P$6,,MATCH(output!$D6,data!$F$5:$P$5,0)):INDEX(data!$F$23:$P$23,,MATCH(output!$D6,data!$F$5:$P$5,0)))*

(INDEX(data!$F$6:$P$6,,MATCH(output!E$5,data!$F$5:$P$5,0)):INDEX(data!$F$23:$P$23,,MATCH(output!E$5,data!$F$5:$P$5,0))<>"")*

(INDEX(data!$F$6:$P$6,,MATCH(output!E$5,data!$F$5:$P$5,0)+1):INDEX(data!$F$23:$P$23,,MATCH(output!E$5,data!$F$5:$P$5,0)+1)<>

INDEX(data!$F$6:$P$6,,MATCH(output!E$5,data!$F$5:$P$5,0)):INDEX(data!$F$23:$P$23,,MATCH(output!E$5,data!$F$5:$P$5,0)))),"")