Mean of annual increase in sale from 2003 to 2008 (rupees in lakhs) is:

Mean of annual increase in sale from 2003 to 2008 = (Sale in 2008 - sale in 2003 )/ (Difference in years)
Mean of annual increase in sale from 2003 to 2008 = 10.5 - 8.5/ 5 = 0.4