Finance Minister P Chidambaram yesterday said he looks forward to seeing the number of retail investors increasing from 1.6 crore at present to 15 crore.Addressing the 20th anniversary celebrations of the National Stock Exchange of India Ltd in Mumbai yesterday, the finance minister said there is an urgent need to increase retail participation and he looks forward to seeing the number of demat account holders grow from 1.6 crore to 15 crore.Securities & Exchange Board of India, Chairman U K Sinha congratulating NSE for its achievements, he said NSE is a symbol of confident India and ready to take up all the challenges that emerging global economies are going to pose to us.