Power BI Measure creation

HI all,

I have a dataset , in which i have many columns which indicates, sales of various products for different months, one column for one product , on emonth and like wise.

The rows contains, various distributers of various companies which have been further classifed based upon location, trading are etc.

I want to create a measure which will show me change in market share of each company , product wise wr.t last year same month. 

i further want to drill this down on the basis of various paramters like class of market, district etc.

Can any one help me.

this is how my data set look like.

grateful if anyone can help

Regards

Abhinav